It is forbidden to add onto the mitzvot. This includes extending a mitzva in time (such as adding an extra day to a holiday), increasing its quantity (such as adding a fifth species to one’s lulav, or a fifth biblical text inside one’s tefillin), or creating a new mitzva. An obvious question arises: how then could our Sages prohibit actions that were not prohibited by the Torah, such as eating chicken with milk? Some answer that the prohibition of Bal Tosif applies only if those making an addition claim that it is a mitzva in the Torah. No one ever claimed that eating chicken with milk is biblically prohibited. Others state that the law of Bal Tosif applies only to adding positive commandments. In contrast, our Sages were allowed to prohibit additional things. This answer, though, does not explain how the Sages were permitted to create the holidays of Purim and Chanukah. An example of extending a mitzva in time is sitting in the sukkah on Shmini Atzeret, the day which follows Sukkot and on which there is no mitzva to sit in the sukkah (at least in Israel; it is more complicated in the Diaspora). Some Rishonim write that one may do so if he makes sure there is a heker, something unusual, to make it clear that he is not trying to fulfill a mitzva. Along the same lines, Rav Kook states that a heker was necessary for the rabbinically-added holidays, so no one could confuse them with biblical mitzvot. Thus, Purim is celebrated on different dates depending upon whether or not one lives in a walled city. There is no comparable rule for any other mitzva. And Chanukah lighting has different levels of observance – the minimal requirement, the enhanced level, and the extra-enhanced level. This too is unique. Two types of additions do not constitute a problem of Bal Tosif according to most opinions. One type is adding in frequency. For example, performing the same mitzva numerous times a day is not prohibited. A second type is broadening the ranks of those who perform a mitzva. For example, a woman is allowed to perform a mitzva from which she is exempt. Nevertheless, there is an opinion that even these two types transgress the prohibition of Bal Tosif, if the person performing an extra mitzva mistakenly believes the Torah mandates it.

The verse instructs us to “Bless the Lord your G-d for the good land” (Devarim 8:10). Our Sages (Berachot 48b) extrapolate from here that the Torah requires three blessings to be included in Birkat HaMazon. The first blesses G-d for providing food (Birkat HaZan), the second blesses G-d for the Land of Israel (Birkat HaAretz), and the third blesses G-d for the rebuilding of Jerusalem (Boneh Yerushalayim). If they are based on the verse, how can the Talmud also tell us that Moshe instituted the first blessing, Yehoshua the second, and David and Shlomo the third? It must be that while the content was established at Sinai, the precise words that we recite were formulated by Yehoshua, David, and Shlomo. Since Birkat HaZan was instituted by Moshe Rabbeinu, it is surprising that some versions of the blessing include the verse: “You open your hand and satisfy the desires of every living thing” (Tehillim 145:16). After all, Tehillim was written by King David, who lived much later than Moshe. The likely explanation is that some of the verses of Tehillim were formulated at an early stage, and King David wrote them down at a later stage. This is borne out by the language used in Birkat HaZan to introduce the verse: “As it is said, ‘You open your hand,’” and not “As it is written, ‘You open your hand.’” As we mentioned, the specific formulation of the blessings was originally different from what we recite today. A person could have fulfilled his obligation (for Birkat HaZan) by saying in Aramaic, “Blessed is the merciful One, King, the Creator of this bread.” Along the same lines, when someone sings Tzur MiShelo – the Shabbat song whose structure is parallel to that of Birkat HaMazon and incorporates the same themes – it is possible that he has fulfilled his obligation to recite Birkat HaMazon. Accordingly, perhaps a person should have in mind when he sings Tzur MiShelo that he does not intend to fulfill his obligation. This way, he ensures that his fulfillment of the mitzva takes place only when he recites the classic Birkat HaMazon.

During the morning prayer service, one may not pause or interrupt between the blessing of redemption (Ga’al Yisrael), and the recitation of the Amidah. Even standing silently between them is prohibited. However, there is also a halacha that one must respond with an Amen after hearing a blessing. Thus, it would seem that someone who hears the chazan (cantor) complete the blessing of Ga’al Yisrael must answer Amen. But then he is creating an interruption between the blessing and the Amidah! What’s a person to do? Some answer that saying Amen to Ga’al Yisrael is like saying Amen after one’s own blessing. In general, a person does not say Amen to his own blessing. However, if he is concluding a subject the Amen is considered part of the blessing and thus is not considered an interruption. (The classic example of this is in Birkat HaMazon, when we conclude our own blessing of “Boneh Be-rachamav Yerushalayim” by saying Amen.) Perhaps the Amen after Ga’al Yisrael is in the same category. Others insist that the reciting of Amen at this point is an interruption and should be avoided. How can a person avoid taking sides in this disagreement? The poskim offer three suggestions: 1. The person praying should try to reach Ga’al Yisrael a little before the chazan. He can then wait, recite Amen to the chazan’s blessing, then recite the blessing himself, and immediately begin the Amidah. However, this solution is not without its problems. First, one is not supposed to pause in the middle of the blessings following Keriat Shema. Second, ideally one is meant to begin the Amidah at the same time as the chazan. 2. The person praying should recite the blessing together with the chazan. In such a case, he is not required to say Amen, as a person does not say Amen to his own blessing. However, as we have seen, there is an opinion that in the case of Ga’al Yisrael a person does say Amen to his own blessing. 3. The person praying should start the Amidah before the chazan. Once someone is in the middle of the Amidah, he does not respond Amen under any circumstances. However, once again, this means one is not beginning the Amidah with the chazan. A fourth solution is very commonly followed nowadays. Namely, the chazan recites Ga’al Yisrael under his breath. Since no one hears the blessing, no one needs to answer Amen. Interestingly, this practice is not mentioned anywhere in the literature. Can it be that there truly is no source for it?

A cup of wine is normally part of the circumcision ceremony. What is to be done when a brit milah takes place on Tisha BeAv and everyone is fasting? There are various opinions. 1. Early authorities cited by the Ba’al HaItur say that the blessing is made over the wine, but the wine is then put aside until the fast is over, at which point someone drinks it. Many Rishonim object to this because of the length of time which elapses from the recitation of the blessing until the actual drinking of the wine. Additionally, if the wine spills in the interim, the blessing will have been made in vain. 2. Some say that wine is not part of the ceremony on Tisha BeAv. 3. Others agree but add that once the blessing over wine is left out, the blessing that is generally recited after the brit should also be left out. 4. Still others posit that wine should be used, and children should be given it to drink. Some object because they feel that doing so might get the children used to drinking on the fast. However, advocates of this approach maintain that since a Tisha BeAv circumcision happens only infrequently, no bad habit will be ingrained as a result. 5. Some believe that a taste of the wine should be given to the infant who is being circumcised. There is certainly no concern in this case that the baby will acquire a bad habit. There are many additional issues which relate to Tisha BeAv. Let us hope for the time when Tisha BeAv will become a joyful day, following the coming of the Messiah and the redemption of the Jewish people.

If a person has taken a vow (neder) but later regrets having done so, he may approach a rabbi to have it annulled. The Hebrew word for annulment is hatarah. Some Rishonim explain that this is related to the word le-hatir, to untie. Undoing a vow is like untying a knot. Others explain that it is related to heter (permissible) as opposed to issur (forbidden). According to them, Hatarat Nedarim means permitting the behavior that had been forbidden by the vow. There is a disagreement among the Tannaim as to the source for Hatarat Nedarim. Some say the source is the verse (Bamidbar 30:3), “He shall not break his pledge” (Lo yachel devaro). They expound: The one who undertook the vow cannot forgive (mochel) it, but someone else can forgive it for him. The other opinion is that Hatarat Nedarim has no basis in the written Torah at all. Rather, Moshe taught the people orally that when the verse says, “He shall not break his pledge,” it means one should not flippantly disregard his vow. Instead, if he truly regrets it and wishes to undo it, a rabbi can do it for him. The idea that there is no clear biblical source for Hatarat Nedarim is expressed in the Mishnah with the phrase “it is floating in the air” (Chagigah 1:8). When a rabbi annuls a vow, the annulment takes effect retroactively. It is as if the person never made the vow at all. In contrast, when a husband cancels his wife’s vow (Hafarat Nedarim), it takes effect only from the time he becomes aware of the vow and cancels it. How is a vow annulment actually done? The person who made the vow stands in front of one rabbi or three laymen. He explains that he regrets having made the vow, and would not have made it if he had realized all the consequences. They then say to him, “The vow is annulled,” “The vow is forgiven,” or anything similar. Some require that the phrase be recited three times, but this is just to make it feel more serious. According to the letter of the law, though, saying it once is sufficient.

Some say that Pinchas is the same person as Eliyahu Ha-navi (the prophet Elijah). We await his coming, as promised by the prophet Malachi, with great anticipation. Eliyahu will provide answers to all our questions, clarifying laws as well as facts. Thus, the word “teiku,” sometimes found in the Talmud following an unresolved question, is understood in folk etymology as an acronym for “Tishbi yetaretz kushiyot u’ba’ayot” (“Eliyahu will resolve all questions and difficulties”). Here is an example of a law to be clarified. When collecting a debt, do we leave the debtor the items which he needs to support himself? After all, when people donate to the Beit HaMikdash, we take their needs into account. Does this apply to debts owed to people as well? The Talmud (Bava Metzia 114a) records that this question was once answered by Eliyahu based on a gezeirah shavah. (By the way, his view was not accepted by all. Even those who chose to accept his view were not doing so because he was a prophet. As we know, the Torah is not in heaven, nor is a prophet permitted to make new laws. Rather, Eliyahu was no less a Torah scholar than anyone else, and might have even been better than most.) Here are some examples of facts with which Eliyahu will help us. He will clarify whether certain terumah has become impure, and the status of a piece of meat which was out of a Jew’s sight. He will be able to adjudicate monetary disputes in which a rabbinic court could not reach a decision and the money was held in abeyance. These cases are all very specific. Eliyahu will also clear up some general doubts found in rabbinic literature about how things work: Do people base a meal (kovea seudah) on wine in the same way that they do on bread? Would a dead person have allowed certain disrespect of his body on the part of his heirs? May we write tefillin on the skin of a kosher fish, or is it considered disgusting? To resolve these doubts, we will rely on the prophetic power of Eliyahu, whose arrival we eagerly await.

When Bilaam noticed that the openings of the Jews’ tents did not face each other, he said, “These people deserve to have the Divine Presence rest upon them.” This is the basis of the halacha which prohibits a person from installing a window that faces his neighbor’s window. Even if the neighbor waived the right to object, and gave him permission to install it, that willingness is irrelevant since the result is immodest. Alternatively, some explain that the reason the neighbor’s willingness is not good enough is because at a later date the neighbor may say, “At first I thought I could live with it, but now I realize that I cannot.” This restriction even applies to a person installing a window that overlooks a jointly-owned courtyard. True, he could argue that it should not matter to anyone if he puts in a window there, since in any case he can go into the courtyard and see what is going on there. Nevertheless, the neighbors may object, “If you are with us in the courtyard, we can hide from you; however, if you are watching us through the window, we are not aware of it (and cannot protect ourselves).” Based on this reasoning, neighbors can object to someone installing a window which faces the courtyard, maintaining that they do not want to be tempted to peek into his window. Also for this reason, a person may not install a window which faces the public domain, even if he says he has nothing to hide and is not worried about people looking into his home.

In Parshat Chukat, the Torah refers to the mitzva of the Parah Adumah (Red Heifer) as a chok, a mitzva that seemingly has no rational explanation. The Talmud cites a verse (Vayikra 18:4), “You shall follow My commandments (chukotai),” and comments: “These are the decrees of the King and there is no explanation for them… You do not have permission to think about them” (Yoma 67b). Does this really mean that there is no rationale for the mitzvot? Could it mean that we have no way to understand the mitzva’s rationale, but there is a rationale known to G-d? If there is such a rationale, why shouldn’t it be revealed to humanity? Possibly because there were mitzvot whose reasons were revealed (specifically, that the king should not have too many wives lest they lead his heart astray, or too many horses lest he return to Egypt), and this led to the downfall of a great leader (Shlomo). On the other hand, we could argue that since reasons were given for those mitzvot, and for many others besides (such as Shabbat and tzitzit), this would seem to imply that all mitzvot do have a rationale. If the reason is not revealed, that is because it does not necessarily explain all the can be found within a given mitzva. Thus, King David proclaims, “I have seen that all things have their limit, but Your commandments are broad beyond measure” (Tehillim 119:96). This may be at the root of the disagreement between Rabbi Shimon and Rabbi Yehudah as to whether we are permitted to seek reasons for mitzvot. Many Rishonim offer rationales for mitzvot (including the Rambam in both the Mishneh Torah and the Moreh Nevuchim). It would seem that they side with Rabbi Shimon, who permits seeking reasons for mitzvot. According to these Rishonim, not only is it permitted, but it is a good idea to explore the rationale for the mitzvot. However, other Rishonim disagree and say that this is what our Sages warned us about when they said regarding a prayer leader (Mishnah Berachot 5:3), “Someone who says ‘Your mercy extends to a bird’s nest’ should be silenced, because he makes it seem like G-d’s ways are compassionate, when in reality they are decrees.”

A minyan, the presence of ten men, is required for those parts of the prayer service that are deemed Devarim She-bikdushah (literally, words of sanctifying). These include Kaddish, Barchu, Kedushah, the repetition of the Amidah, and (according to some) the reading of the Torah, the reading of the Haftarah, and the priestly blessing. This rule is derived from the verse, “I will be sanctified among the children of Israel” (“Ve-nikdashti be-toch Bnei Yisrael”) (Vayikra 22:32). How do we know that the number referred to here is specifically ten, neither more nor less? One way of arriving at ten is through a gezeirah shavah. (This is a method of rabbinic exegesis in which a similar word appearing in two different contexts is used to infer that the details of one context apply to the other.) The word “toch” (“among”) appears in the verse about sanctifying G-d, and in the story of Korach’s rebellion. Regarding the latter, the Torah states (Bamidbar 16:21), “Separate yourselves from among (mi-tokh) this community (edah).” However, there the Torah is referring to a group of 250 people. How is it useful for arriving at the number ten? This involves a bit more exegesis. The word “edah,” which is used in the story of Korach, is also used in reference to the ten spies who spoke badly of the Land of Israel, as we read (Bamidbar 14:27), “How much longer will that wicked community (edah) keep muttering against Me?” We see that the definition of a community is ten. Thus, the community within which we sanctify G-d’s name must be similar to the spies (not in their sinfulness, of course, but in being free, adult males). It should be noted that the above is not a combination of one gezeirah shavah with another (toch-toch and edah-edah), which would possibly break a rule of exegesis. Rather, we learn from the case of the spies in Parshat Shelach that the definition of the word “edah” is ten everywhere it appears. This includes the verse in Parshat Korach, where the word “toch” is associated with ten (through the word “edah”). And a gezeirah shavah (toch-toch) connects that verse with the verse about sanctifying G-d.

Bamidbar 10:9 presents the mitzva of sounding trumpets during wartime (“When you are at war in your land”), and during a time of trouble (“against an enemy who oppresses you”). Some require that both these conditions be present for the mitzva to be in effect. This leads the Avnei Nezer to ask whether we should blow the trumpets only for a voluntary war, or also for a milchemet mitzva (obligatory war). After all, since G-d has guaranteed us a successful outcome, one might posit that it is not considered a time of trouble. During the war against Jericho (which was a milchemet mitzva), they blew the shofar and not the trumpets (Yehoshua 6:2). This would seem to prove that blowing the trumpets is limited to a voluntary war. While some limit the trumpet-blowing to a voluntary war, others offer a different limitation. The Pri Megadim points out that the verse uses the word “be-artzechem” (“in your Land”). He explains that this is the reason that in his time (18th century) the trumpet was not blown for trouble, as this was limited to trouble in the Land of Israel (or, by extension, trouble for the majority of the world’s Jews). With this background, we can understand why Rav Shraga Feivel Frank (HaMa’ayan, 1970) exhorted people to blow trumpets near the Kotel in contemporary times of trouble. He argued that this would fulfill the mitzva. In wartime, the trumpets are sounded as part of a special prayer service designed for this purpose. This prayer service is similar to that of Mussaf on Rosh Hashanah, with verses of Malchuyot (G-d’s kingship), Zichronot (asking G-d to remember), and Shofarot (about times when a shofar was sounded). Some maintain that the trumpets are blown in the battlefield itself, as we see from historical descriptions of the wars of the Maccabees. Similarly, when our soldiers return from war or when they celebrate victory, they should celebrate and sound the trumpet. This is what King Yehoshaphat did when he returned victorious from the wars against Ammon and Moab. As it states, “For G-d had given them cause for rejoicing over their enemies. They came to Jerusalem to the house of G-d, to the accompaniment of harps, lyres, and trumpets” (II Divrei HaYamim 20:27-28). As a result, “The terror of G-d seized all kingdoms of the land when they heard that G-d had fought the enemies of Israel. The kingdom of Yehoshaphat was untroubled, and his G-d granted him respite on all sides” (ibid. 29-30).

The Torah tells us that “The people registered their ancestry by their clans and families” (Bamidbar 1:18). Rashi comments: “They brought their documents of lineage and witnesses to the status o f their birth, each and every one of them, so as to trace his ancestry to the tribe.” Even after these clarifications, some doubts remained in certain cases. For example, a divorcee or widow might have remarried immediately (without waiting the required three months after the death or divorce), in which case the paternity of her child born soon after was uncertain. Halachic literature discusses how to ascertain paternity in such cases. According to the Talmud in Yoma 75a, the manna could be used to establish paternity. The Torah states that each person in a household was entitled to an omer of manna (Shemot 15:15). If the household members gathered more, it would rot. In the case of uncertain paternity, when either of two men might be the father, all that was necessary was to check which of the two households had enough manna for the extra child. That would be the father’s household. May we really clarify someone’s lineage using heavenly signs? Tosefet Yom Ha-Kippurim explains that the rabbinic courts would establish parenthood using conventional halachic principles. The manna was used only to corroborate what they had already established, and to remove any lingering doubts that people may have harbored. Sefer Chasidim describes another interesting method to establish paternity. There was once a question as to which of two boys was the biological son of a man who had died. The people took a bone from the dead man. They filled two cups with blood, one from each boy. They then dipped the bone into each cup of blood. Only the blood of the biological son was absorbed by the bone. Here too, some maintain that this was done only after the courts had already established the facts through conventional methods, and the bone test was used only to corroborate their conclusion and make people feel better about it. Nowadays, we can determine paternity through a simple DNA test. Current decisors discuss the acceptability of this tests. Some write that it should not be relied upon unless classic halachic methods back it up. Others argue that a DNA test may be relied upon absolutely, as can any law of nature to which there are no exceptions. According to them, the test is so reliable that even if witnesses gave testimony which contradicted the DNA evidence, we would reject the testimony and declare them false witnesses.

On Lag BaOmer of a Shemitah year, at some point between the customary bonfire and the haircuts, some knowledgeable people will get up and declare ownerless the etrog jelly that they made after Sukkot. A short while later, they will reclaim their food. Before Shavuot, they will declare ownerless the olives they picked, and then reclaim them. Earlier, before Pesach, they will do the same thing with the wine that was produced through Otzar Beit Din. The pattern is repeated through Shemitah with many types of fruit. These actions are indirectly derived from the verse, “And your cattle and the [wild] beasts in your land may eat all its yield” (Vayikra 25:7). Why is it necessary to specify “the cattle” (i.e., domesticated animals), when the verse also mentions “the beasts in your land”? For if a wild beast may eat of the Shemitah produce, a domesticated animal certainly may! Our Sages use this verse as grounds for the following exposition: “Once the fruits have disappeared from the field and are unavailable for wild beasts, the fruits must disappear from the home as well and be unavailable for domestic animals.” In other words, once there are no more fruits on the tree because they have all either fallen off or rotted, people may no longer hold onto them at home either. Rather, they must dispose of them. This disposal is called biur. It would seem that this biur should be similar to biur chametz, which involves burning the forbidden food. Indeed, there are some who require this (Rambam, for example). However, the generally accepted practice is to remove the fruit from the home and declare them ownerless. After this has been done, it is permissible for the former owner to reclaim them. In theory, of course, someone else could come along in the meantime and acquire the food that had been declared ownerless. Nevertheless, it is rare to find people trying to find a bargain this way. This is likely because those who declare the items ownerless can do so in front of three good friends, and rely on their not taking advantage of the opportunity to acquire the items for themselves. The times mentioned above for declaring certain produce ownerless (before Pesach, on Lag BaOmer, and before Shavuot) were designated by the Sages, based on their estimates when each type was no longer available in the fields for the wild beasts. They designated other times for other fruits. Today, various organizations (such as Machon HaTorah VeHa’aretz) produce Shemitah calendars which detail the specific dates relevant to many different fruits and vegetables.