Musannaf Ibn Abi Shayba 13:2608

Abu Bakr narrated to us, he said: Hashim ibn al-Qasim narrated to us, he said: Ibn 'Utbah narrated to us, he said: Abu Kathir al-Suhaymi narrated to us, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "The two parties to a sale have the option (to rescind) as long as they have not separated from their sale, or unless their sale is by mutual option."