Sahih Muslim
The Book of Jihad and Expedition (Kitab Al-Jihad wal-Siyar)
Book Number: 019 / Hadith Number: 4335
A hadith has been narrated by Salim who learnt it from his father and said: The Messenger of Allah (may peace be upon him) gave us an extra (camel) besides our share of Khums; (and in this extra share) I got a Sharif (and a Sharif is a big old camel).