Musnad Ahmad 266:6

'Abd al-Rahman ibn Mahdi narrated to us, Sufyan narrated to us, from 'Abd Allah ibn 'Isa, who said: 'Ata', a man who used to be at the coast, narrated to me, from Abu Usayd or Abu Usayd ibn Thabit—Sufyan was uncertain—that the Prophet, peace and blessings of Allah be upon him, said: "Eat the oil, and anoint yourselves with the oil, for it is from a blessed tree."