Musannaf Ibn Abi Shayba 13:1796

Abu Bakr narrated to us, he said: Ibn Abi Za’idah narrated to us, from Ash’ath, from al-Hakam, from Ibrahim: That he said: Every condition in a sale is invalidated by the sale, except for manumission (emancipation). And every condition in a marriage is invalidated by the marriage, except for divorce.