Bava Batra 145 - Groomsman's Gifts
It was customary in Talmudic times for friends of a groom to act as his groomsmen, that is, to bring him gifts in celebration of his wedding and to join him for wedding feasts, which lasted for seven days. It was understood that the groom would reciprocate when his groomsmen celebrated their own weddings.
If some of the brothers performed as groomsmen during their father's lifetime - the father providing the necessary funds to do so - then when the original groom reciprocates with gifts of his own - they are returned to the common estate.
Five things were said about a groomsman's gift: its reciprocation is enforceable in court, it is returned only at the time of marriage, it does not involve any question of interest, the seventh year does not cancel it, and the firstborn does not take a double portion of it.
Art: Harmen HALS - Peasants at a Wedding Feast