Just as one may not buy and sell on Shabbat, one may not lend anything or repay a loan. Since these activities often involve writing contracts, there is a concern that engaging in them may lead one to write. Therefore, one who needs to borrow food, clothing, or chairs for Shabbat should formulate his request in a way that makes it clear that he is borrowing the objects as one would borrow from a friend, not as one would borrow money from a bank, as it is unusual keep a written record when borrowing from a friend. Since English does not distinguish between these two types of borrowing (unlike Hebrew, which has “hashala” to refer to borrowing objects and “halva’ah” to refer to monetary lending), one should simply say “Give me” or “Can I have.” If the owner of the item is concerned that the borrower will forget to return it, he may request that the borrower leave something with him, but he should not refer to it as a deposit or collateral, as he would during the week (Shabbat 148a; Rema 307:11). If the borrower mistakenly asked for a loan, the owner may give it to him while clarifying that he may use it temporarily though one may not make a loan on Shabbat (Shulĥan Shlomo 307:15:2).
According to many poskim, one may not give or receive presents on Shabbat because by doing so one transfers ownership of the gift, which resembles commerce (MA 306:15; Birkei Yosef ad loc. 7; MB ad loc. 33). Others maintain that one may give a gift on Shabbat because nobody writes contracts for gifts (Beit Meir based on Rif and Rambam). In practice, we are stringent le-khatĥila and avoid giving gifts on Shabbat, but if it is necessary to fulfill a mitzva, everyone agrees that one may give a gift (SA 658:3-4). Therefore, one may give a gift of utensils or food for a Shabbat meal (MB 306:33). One may also give prizes to children for participating in Torah study, as this is for the sake of a mitzva – to encourage the children to study Torah.
It is proper for one who wants to give a bar mitzva present on Shabbat to perform the act of acquisition (kinyan) before Shabbat. That is, he should request someone else to take the gift, lifting it up (hagbaha) in order to acquire it on behalf of the bar mitzva boy. Thus, the gift is transferred to the boy’s ownership before Shabbat. On Shabbat it may be presented to him, as it already belonged to him prior to Shabbat. If hagbaha was not done, the gift can be left with the boy (who should have in mind not to acquire it) for the duration of Shabbat, and after Shabbat he may officially acquire it (SSK 29:31). Some are lenient and give gifts to a groom on Shabbat, as there is an element of mitzva involved in bringing him happiness (Eliya Rabba; Ĥatam Sofer). In a time of need, one may rely upon them (Seridei Esh 2:26).
One may not use a lottery or other random selection mechanism on Shabbat in order to decide who will receive each portion of food. Since everyone wants the biggest and tastiest portion, there is a concern that people will end up measuring and weighing the portions or speaking about their price. Moreover, it contains an element of gambling. Members of a household may use a lottery, but only as long as the portions are of equal value (Shabbat 148b-149a; SA 322:6; see below 22:8). One may draw lots to determine who will have the privilege of getting an aliya or saying Kaddish, because there is nothing to measure or calculate (MB 322:24).