We are beginning siman 23, regarding the concept of bal tosif and bal tigra. The Chayei Adam writes that it is assur to add to the mitzvos. There are two pesukim which teach us this issur, one says lo sosif and one says lo sosifu. We will need to discuss why there are two pesukim at some point, but we will begin with defining the issur.
The Gra writes that there is an additional issur, not part of our discussion here, against adding entirely new mitzvos beyond the 613. The issur learned from these pesukim regards adding details to an existing mitzvah.
The primary Gemara regarding this issur is found at the end of the third perek of Rosh Hashanah. The Gemara discusses the concept of bal tosif in the context of mitzvos tzrichos kavanah (see shiurim 1413-1420). If we hold that mitzvos tzrichos kavanah on any mitzvah, one may argue that it would be necessary to have kavanah when transgressing bal toseif as well. On the other hand, the Gemara brings a possibility that bal tosif would not require kavanah.
The Chayei Adam brings two possibilities of bal tosif, adding onto the mitzvah while performing the mitzvah, and adding onto the mitzvah afterwards. The Chayei Adam also clarifies that the issur only applies when a person wishes to add to a mitzvah to make it bigger than it is in the Torah. For example, when we sit in the sukkah on the Shemini Atzeres, or eat matzah on the eighth day of Pesach, if a person says that they are adding the eighth day because there is another mitzvah passed down as Torah Shebaal Peh, they are transgressing bal tosif. When we sit in the Sukkah on Shemini Atzeres, or eat matzah on the eighth day, it is not due to the invention of a new mitzvah, but rather due to a safeik as to how to fulfill the mitzvah properly. We are not adding on to the mitzvah, but trying to fulfill the mitzvah as was originally commanded.
Similarly, we know there are two opinions regarding the correct order of the parshiyos in the tefillin, Rashi’s order and Rabbeinu Tam’s order. Each opinion believes the other is not kosher, so some people have the minhag to wear both in order to fulfill the mitzvah according to both opinions. If one decides that both tefillin are acceptable, and they wish to wear both because they have decided that there are two mitzvos to fulfill, they are adding onto the mitzvah and have transgressed bal tosif.
Nowadays, regarding yom tov sheini, we keep yom tov sheini not due to the safeik, but because of a takanas Chazal. Be’ezras Hashem, we will explain how that fits into this discussion in the upcoming shiurim.
Summary
- Bal tosif and bal tigra are the chiyuvim not to alter a mitzvah by adding or detracting from it.
- Bal tosif can apply by adding onto a mitzvah while performing it, and by adding onto a mitzvah afterwards.
- The issur applies when one wishes to make a mitzvah larger than the commandment in the Torah, not when they add to it due to a safeik as to how the mitzvah is correctly performed.
