Musnad Ahmad 27:587

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from 'Abdullah ibn Dinar, I heard Ibn 'Umar say: A man from Quraysh used to be cheated in sales, so he mentioned that to the Prophet, peace and blessings of Allah be upon him. The Prophet, peace and blessings of Allah be upon him, said to him: "Say: 'There is no deception.'"