Musnad Ahmad 25:39

Muhammad ibn Salamah narrated to us, from Ibn Ishaq, from Dawud ibn Husayn, from Ikrimah, from Ibn Abbas, who said: "The Messenger of Allah, may Allah bless him and grant him peace, returned his daughter Zaynab to her husband, Abu al-As ibn al-Rabi', by the first marriage contract, and he did not introduce anything new."