Musannaf Ibn Abi Shayba 13:2607

Abu Bakr narrated to us, he said: Al-Fadl ibn Dukayn narrated to us, he said: Hammad ibn Zayd narrated to us, from Jamil ibn Murrah, from Abu al-Wadi’, from Abu Barzah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "The two parties to a transaction have the option (to rescind or confirm) as long as they have not separated."