Musannaf Ibn Abi Shayba 16:45

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Harun ibn Abi Ibrahim, from Abdullah ibn Ubayd ibn Umayr, that a man asked his father about the rabbit. He said: "There is no harm in it." He said: "It menstruates." He said: "The One who knows its menstruation knows its purity, and it is merely one of the pregnant ones."