Musannaf Ibn Abi Shayba 28:785

Isma'il ibn 'Ulayyah narrated to us, from Ibn 'Awn, who said: I read a book mentioning the *safiyy* (the chosen portion), so I said to Muhammad: "What is the *safiyy*?" He said: "It was a head [of spoils] that would be chosen for the Prophet, may Allah bless him and grant him peace, before anything else, and then his share would be drawn for him along with the Muslims."