Translation:Shulchan Aruch/Choshen Mishpat/266

Paragraph 1- The lost item of an idolater is permitted, as the verse states, “the lost item of your brother.” If one returns such a lost item, he has violated a sin because he is strengthening the hands of the sinner. If he returned it to sanctify God’s name in order that Jews be glorified and people know they are trustworthy, that is praiseworthy. In a situation where there will be a desecration of God’s name, the idolater’s lost item would be forbidden and the finder would be required to return it. In all places one many bring in their vessels as he would Jews’ vessels in order to keep the peace.

Paragraph 2- One is required to return the lost item of a Jew, even if the owner of the item is wicked and eats non-kosher meat out of desire. If one eats non-kosher meat spitefully, however, he is a heretical Jew, and one is prohibited from returning a lost item to heretics, idolaters or Jews who desecrate the Sabbath public just as they are prohibited from returning to idolaters.

Paragraph 3- The laws of returning a lost item to one who has sworn off benefits of another are discussed in Tur Yoreh Deah Siman 221.

Paragraph 4- One does not return a vicious cat that damages youngsters. Rather, whomever finds it can kill it and acquire its hide.

Paragraph 5- If one’s father told him not to return a lost item, he would not listen to him.