As you are leaving the synagogue on a Shabbat morning, you find a diamond ring on the floor. The loss is publicly announced in the synagogue three Shabbatot in a row. But no one steps forward to claim it. According to Jewish law, you, the finder, are a shomer aveidah, a guardian of lost property and you must guard the ring in your possession until the owner claims it from you. So you take the ring home and place it in a safe. When the owner finally comes forward and claims the ring, you go to the safe to retrieve it, but alas, the ring is gone. Somebody, you don’t know who, stole the ring. Are you now liable to pay the owner the value of the stolen ring?
That all depends on the status the halacha attributes to the shomer aveidah. There are two possibilities. The shomer aveidah either has the status of a shomer chinam, an unpaid bailee, or he has the status of a shomer sachar, a paid bailee. A shomer chinam is a person who volunteers to guard a deposited item free of charge. Accordingly, the halacha does not hold the shomer chinam responsible for the theft of the article so long as he guarded it in a responsible manner. A shomer sachar is a person who receives compensation for guarding a deposited item. Accordingly, the halacha holds the shomer sachar responsible for the theft of the article.
Is a shomer aveidah considered a shomer chinam or a shomer sachar?
According to Rabbah, the shomer aveidah is a shomer chinam because he receives no compensation for fulfilling the mitzvah of guarding lost property. According to Rav Yoseph, the shomer aveidah is a shomer sachar.
The reasoning of Rav Yoseph is as follows: While guarding the lost property, the shomer aveidah is performing a mitzvah. Now, the rule is “ha’osek bemitzvah patur min hamitzvah,” if you are busy performing a mitzvah you are exempt from performing another mitzvah. Therefore, explains Rav Yoseph, the shomer aveidah is exempt from the mitzvah of giving charity to the poor. The amount he saves in charity is deemed to be the payment he receives for guarding the lost property and the shomer aveidah is therefore a shomer sachar. The Shulchan Aruch rules that as long as the lost property is in his possession, based on the dictum of ha’osek bemitzvah patur min hamitzvah, the shomer aveidah is a shomer sachar. The Rambam rules that as long as he is preoccupied with taking care of the lost property in his possession, based on the dictum of ha’osek bemitzvah patur min amitzvah, the shomer aveidah is a shomer sachar.
Clearly, one’s liability for guarding the lost ring depends on the interpretation of the Talmudic dictum of osek bemitzvah.
Does the osek bemitzvah exemption apply only in circumstances where it is impossible to perform both mitzvot simultaneously, as in the case when the poor man comes by when you are preoccupied with polishing the diamond, a situation we shall refer to as the “Impossible Case”? Does it also apply where it is easy to perform both, as in the case when the poor man comes by when the ring is lying locked away in the safe, a situation we shall refer to as the “Easy Case”? Does it apply where it is difficult yet still possible to perform both, as in the case when the poor man comes by when you are holding the ring in one hand, a situation we shall refer to as the “Difficult Case”?
According to Tosafot and the Rosh, the osek bemitzvah exemption applies only in the Impossible Case. Clearly, argue Tosafot, one is not exempt from mitzvot just because one wears tzizit all day or because one is warehousing somebody’s lost property. Rashi holds that the osek bemitzvah exemption also applies in the Easy Case. Accordingly, a person travelling by day on Sukkot to perform the mitzvah of visiting his rabbi, is, says Rashi, exempt from the mitzvah of eating and sleeping in the sukkah when he sojourns at night.