Musannaf Ibn Abi Shayba 7:135

Umar ibn Talha narrated to us, from Asbat ibn Nasr, from Simak, from Ikrimah, from Ibn Abbas, from Umar, that he said: "I swore by my father, and suddenly there was a man behind me saying, 'Do not swear by your fathers.' So I turned around, and behold, it was the Messenger of Allah, may Allah bless him and grant him peace."