Tribute, Spoils, and Rulership (Kitab Al-Kharaj, Wal-Fai' Wal-Imarah)
Dawud :: Book 19 : Hadith 2945
Narrated Abdullah ibn Umar:
Zayd ibn Aslam said: Abdullah ibn Umar entered upon Mu'awiyah. He asked: (Tell me) your need, AbuAbdurRahman. He replied: Give (the spoils) to those who were set free, for I saw the first thing the Apostle of Allah (peace_be_upon_him) did when anything came to him was to give something to those who had been set free.