Musannaf Ibn Abi Shayba 9:443

Ali ibn Mushir narrated to us, from al-Shaybani, from Abdullah ibn Shaddad, who said: I was sitting with Ibn Abbas at Zamzam when a man came to him and mentioned that he had caused his wife to miscarry, and he claimed that she had committed adultery. Ibn Abbas said to him: "How evil is what you have done! If she did what she confessed to herself, then keep your wife. But if she did not do it, then let her go her way."