Sahih Bukhari
Hunting, Slaughtering
Volume: 007 / Book Number: 067 / Hadith Number: 416
Narrates 'Abdullah bin Mughaffal:
While we were besieging the castle of Khaibar, Somebody threw a skin full of fat and I went ahead to take it, but on looking behind, I saw the Prophet and I felt shy in his presence (and did not take it).