If one finds something that belongs to someone, he is obligated to make
efforts to return it. As with other mitzvos, there are various halalchos
involved in fulfillment of this mitzvah. We will enumerate a few of them
When a person finds an item with identifying marks on it, he should not
delay in announcing the find, because if he does the owner may give up in
the interim and the mitzvah opportunity will be lost (Rambam, Hilchos
If an item does not have identifying marks, it should sometimes be left
where it was found for the owner to return to it.
When there is a question over whether or not the owner has already given
up on finding the item, it is suggested that one who finds it should pick
it up on condition that he finds the owner. If the owner is not found,
the finder reserves the right to acquire it for himself after the owner
gives up (Pischei Choshen, p. 256).
If one doesn't find the owner, he can eventually record the information
and sell the item or use it in the meantime (Iggros Moshe, Choshen Mishpat
If you see someone's car lights left on, which can drain the battery, you
have a mitzvah obligation to notify the owner.
Helping to heal someone (returning one's lost health) and helping with a
shidduch ("returning" one's other half) are also included in this mitzvah.