Musnad Ahmad 834:28

Sulayman ibn Dawud Abu Dawud narrated to us, Shu'bah narrated to us, from Humayd ibn Hilal, from Abdullah ibn Mughaffal, who said: "A leather bag of fat was lowered on the day of Khaybar. I leaped and took it, then I looked and behold, the Prophet, peace and blessings of Allah be upon him, was there, so I felt shy before him."