Musnad Ahmad 834:16

'Affan narrated to us, Shu'bah narrated to us, from Humayd ibn Hilal, from 'Abdullah ibn Mughaffal, who said: "We were besieging the fortress of Khaybar, and a man threw a leather bag containing fat toward us. I went to take it, then I saw the Prophet, peace and blessings of Allah be upon him, and I felt shy."