Musnad Ahmad 27:1286

Ali ibn Bahr narrated to us, Salih ibn Qudamah ibn Ibrahim ibn Muhammad ibn Hatib al-Jumahi Abu Muhammad narrated to us, Abdullah ibn Dinar narrated to me, from Ibn Umar, from the Prophet, peace and blessings of Allah be upon him, who said: "Whoever is to take an oath, let him not take an oath except by Allah." Quraysh used to take oaths by their fathers, so he said: "Do not take oaths by your fathers."