Musnad Ahmad 658:24

Abu al-Walid and 'Affan narrated to us, they said: 'Ubayd Allah ibn Iyad narrated to us, he said: Iyad ibn Laqit narrated to us, from al-Bara' ibn 'Azib, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "When you prostrate, place your palms [on the ground], and raise your elbows." Abu 'Abd al-Rahman said: Ja'far ibn Humayd narrated it to us, he said: 'Ubayd Allah ibn Iyad narrated to us, from his father, from al-Bara', the like of it.