Musnad Ahmad 27:1013

Ubayd ibn Abi Qurrah narrated to us, Sulayman—meaning Ibn Bilal—narrated to us, from Abdullah ibn Dinar, 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, the Mighty and Majestic." Quraysh used to take oaths by their fathers, so he said: "Do not take oaths by your fathers."