פירוש על קידושין 32:4

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.

The fact that R. Shimon specifies four means that there are no other ways for her to go free. He did not leave anything out.

We can’t say that he only teaches things that are fixed in time or amount because “signs” of puberty are not fixed.