Musnad Ahmad 648:21

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from Salamah ibn Kuhayl, from Dharr, from Ibn ‘Abd al-Rahman ibn Abza, from his father, that a man came to ‘Umar. Ibn Ja‘far mentioned the like of the hadith of al-Hakam, and he added: And Salamah was in doubt, he said: I do not know, he said: Does it contain "the elbows" or "up to the palms"? ‘Umar said: Yes, we shall entrust you with what you have taken charge of.