Musnad Ahmad 30:3791

Muhammad ibn Abdullah ibn al-Zubayr narrated to us, Yahya—meaning ibn Ayyub—from the descendants of Jarir, narrated to us, he said: I heard Abu Zur'ah mentioning from Abu Hurayrah, he said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "The two parties to a sale shall not separate from a sale, except by mutual consent."