The Torah commands in Parashat Re’eh (Debarim 13:1), “Lo Tosef Alav” – that we may not add onto Misvot.
The Rishonim disagree in defining this prohibition. The Rambam, in Hilchot Mamrim (2:9), maintains that this command is violated by considering a law one of the Torah’s laws when in fact it isn’t. For example, the Rambam writes, if a Rabbi or court rules that eating chicken with milk is forbidden by force of Torah law, then the Rabbi or Rabbis have violated this Torah prohibition. The Torah command forbidding mixing meat with milk applies only to the meat of animals; the Sages extended this Biblical prohibition to include also poultry. Therefore, according to the Rambam, if one rules that mixing poultry with milk transgresses a Torah command, he is guilty of “Bal Tosif” – the prohibition against adding onto the Misvot – because he has sought to add a Misva to the Torah.
Most Rishonim, however, dispute the Rambam’s position, and maintain that “Bol Tosif” forbids adding to one of the Torah’s Misvot Aseh (affirmative commands), such as by wearing two pairs of Tefillin simultaneously instead of just one, or by making the Tefillin Shel Rosh with five compartments instead of four. Other examples include taking a second Lulab when fulfilling the Misva of the four species on Sukkot, or residing in the Sukka after Sukkot with the intention of fulfilling the Misva of Sukka. According to these Rishonim, the prohibition of “Bal Tosif” forbids not considering something a Biblical command, but rather adding to the performance of one of the Torah’s affirmative commands.
The Sefer Ha’hinuch, in explaining this view, clarifies that one does not violate “Bal Tosif” by repeating the performance of the Misvat Aseh multiple times within the time in which it applies. For example, it is entirely permissible to take the four species even one hundred times each day of Sukkot, or blow the Shofar one hundred times on Rosh Hashanah. The later commentators explain that “Bal Tosif” forbids not repeating a Misva, but changing the essence of a Misva. The Torah allows repeating a Misva act multiple times, but forbids changing the Misva, such as by wearing a second pair of Tefillin, adding a second Lulab, or residing in the Sukka beyond the seven days of Sukkot. Moreover, the commentators explain, from the outset, the Torah never imposed a limit on the number of times a person can fulfill a Misva. When it commanded to take the Lulab on Sukkot, for example, the intent is that the Lulab must be taken at least once; the Torah did not set a maximum limit on the number of times a person can take the Lulab. And the same is true of other Misvot. Therefore, as long as a person is still within the Misva’s time-frame, he may fulfill the Misva multiple times, and this does not violate the command of “Bal Tosif,” because the Torah never placed a limit on the number of times a Misva act may be performed. After the time for the Misva has passed, however, performing the Misva act with the intention of fulfilling a Misva constitutes an addition to the Misva, and is thus prohibited.
The Sefer Ha’hinuch notes, interestingly enough, that adding a fifth species when taking the Arba Minim (four species) on Sukkot does not transgress the command of “Bal Tosif.” At first glance, this would certainly appear as a classic example of adding onto the performance of a Misva, no different than wearing two pairs of Tefillin, or wearing Tefillin Shel Rosh with five compartments instead of four. The Sefer Ha’hinuch explains that in the case of the Arba Minim, the fifth species can be seen as disconnected from the four species. Halacha does not require binding the four species together when fulfilling the Misva (“Lulab En Sarich Eged”), and thus we do not regard the four species as comprising a single entity. As such, even if one did bind the four species together with a fifth species, he has not added onto the Misva, because we can disregard the fifth species; it is not considered to be included as part of the Misva act. This case thus differs from that of Tefillin with five compartments, as this constitutes a change to the entity of the Tefillin, and thus violates the prohibition of “Bal Tosif.”
The reason for this command is that Hashem’s commands are perfect the way they were given, and adding onto a Misva gives the impression that one feels the Misvot require modification. Just as one would never add to the dose of medicine prescribed by a doctor, as this could cause harm, we are likewise forbidden from adding to the Misvot which G-d “prescribed” for us. We must accept precisely what Hashem has commanded us to do, without seeking to add onto or modify His commands in any way.
This Misva applies at all times and in all places, and is binding upon both men and women. One who violates this command by adding onto a Misvat Aseh is liable to Malkut (according to the opinion of most Rishonim, as discussed).
The Torah in this verse introduces also the converse command – “Bal Tigra,” forbidding diminishing from a Misva. The Sefer Ha’hinuch gives the example of “Matan Damim” – the placement of sacrificial blood on the Mizbe’ah (altar). He references the debate among the Tannaim concerning the case of blood of two sacrifices that was mixed. Specifically, the blood of a Bechor (firstborn animal, that is offered as a sacrifice), which requires a single sprinkling on the altar, was mixed with the blood of an Ola (burnt-offering), which must be sprinkled four times. The question arises as to what should be done with this blood. Rabbi Yehoshua ruled that the blood should be sprinkled only once, because if it would be sprinkled four times, the Kohen would be in violation of “Bal Tosif,” by sprinkling the blood of the Bechor more than required. Rabbi Eliezer felt that to the contrary, the blood should be sprinkled four times, because if it is sprinkled only once, this would be violation of “Bal Tigra,” sprinkling the blood of the Ola less than required. Rabbi Yehoshua explained that it is preferable to violate “Bal Tigra” passively, by sprinkling the blood of an Ola fewer times than required, rather to violate “Bal Tosif” actively, by sprinkling the blood of the Bechor more times than required. In any event, the Sefer Ha’hinuch brings this discussion as an example of the violation of “Bal Tigra” – diminishing from a Misva.
The Abneh Miluim (Rav Aryeh Leib Heller, Galicia, d. 1812) raises the question of why the Sefer Ha’hinuch chose this specific example of “Bal Tigra.” Seemingly, there are numerous different ways in which one can detract from the performance of a Misva. Why did the Sefer Ha’hinuch resort to this example?
The Abneh Miluim answers that the Sefer Ha’hinuch selected this particular Halacha because sprinkling the blood of an Ola only once actually fulfills the Misva, only not the way the Misva is optimally to be fulfilled. If one diminishes from a Misva in a manner that does not satisfy the obligation, then this does not violate “Bal Tigra,” because the individual performed a Halachically meaningless act. If, for example, a person wears Tefillin Shel Rosh that consists of only three compartments, then he does not wear Tefillin, and thus this act has no significance whatsoever. As such, it does not transgress “Bal Tigra.” This prohibition is violated only when one chooses to diminish from a Misva in a manner that fulfills the obligation. The Sefer Ha’hinuch therefore gave the example of sprinkling the blood of the Ola just once, which fulfills the Misva but in a diminished manner.
The reason for this Misva, of course, is that one may not assume the right to diminish from what Hashem has told us to do. The Sefer Ha’hinuch notes that if the Torah forbade adding onto Misvot – which one might intuitively have thought is virtuous, an attempt to serve G-d even more than required – then certainly, it is forbidden to diminish from the Misvot, and do less than Hashem commanded us to do.