Commentary for Kiddushin 32:3

Upon going free a slave receives a gift from his master. There are a total of four different ways of going free (to be listed below), three for a man and three for a woman. “Signs” of puberty free a woman but not a man and the death of the master of a slave who had his ear bored frees a man but not a woman (she cannot have her ear bored). But according to Resh Lakish there would be another way for a woman to go free—the death of her father.