Engagement in Mitzvah Exempts Others

Rabbi Israel Chait

Written by a student

The Mishnah (Succah 25a) teaches the principle of “Osek b’mitzvah, pattur min hamitzvah; One engaged in a mitzvah is exempt from other mitzvahs.” Rabbeinu Nissim (RIF pg. 11a “Ika Limaydak”) explains that we do not apply this exemption to one wearing tefillin, who is then approached by a poor man for money: wearing tefillin does not exempt him from the mitzvah to give charity. This case is contrasted to another: a few rabbis were en route to visit their leader, which is a mitzvah. The Succos holiday coincided with their journey, which exempted them from dwelling in a succah. Why are these men exempt? Let them stop, build a succah, and continue their journey. What are the rules in applying the principle “One engaged in a mitzvah is exempt from other mitzvahs?”

Rabbeinu Nissim distinguishes these two cases. Wearing tefillin is considered “fulfilling” (mikayame) the mitzvah, but passively, unlike those on a journey which is an “active engagement” (osek) in mitzvah. Rabbeinu Nissim formulates his reasoning: 

“Whomever is involved in God’s work, Torah does not burden him to fulfill other mitzvahs, even though it is possible to perform both.”  

The key phrase is “involved in God’s work.” Rabbeinu Nissim means that man’s purpose is “awareness of God.” Once man is actively engaged in a mitzvah, he is aware of God and another mitzvah is thereby made obsolete. The engagement in mitzvah prevents another Torah obligation from devolving upon the person. Even at night, those travelers are exempt from succah, as Rabbeinu Nissim says, “they are called (mikru) involved in mitzvah.” He says, they are “called” because they are not actually traveling at night. Nonetheless, they have the “designation” as those engaged in mitzvah. Designation is different from actual performance, but it exempts equally.

Rabbeinu Nissim continues (Ibid., following commentary “Umihu”): 

“If the second mitzvah can be fulfilled with no deviation in performing the first, and with no toil [like the tefillin case above] then one must certainly perform the second mitzvah too [giving charity to the poor man].”

In this case, it would be a degradation to the mitzvah  (bizuy mitzvah) of charity to abstain from charity when nothing prevents him. Wearing tefillin can be performed in an uncompromised manner, even while giving charity. But when those traveling to see their leader or rebbe didn’t fulfill succah, there is no degradation of the mitzvah of succah. They were involved in mitzvah, there is toil to build a succah, so they were exempt.