Musannaf Ibn Abi Shayba 13:896

Abu Bakr narrated to us, he said: Ibn ‘Uyaynah and Yahya ibn Sa’id narrated to us, from Muhammad ibn ‘Ajlan, from ‘Awn ibn ‘Abd Allah, from Ibn Mas’ud, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "If the two parties to a sale disagree, then the statement is what the seller says, and the buyer has the choice."