Jihad (Kitab Al-Jihad)
Dawud :: Book 14 : Hadith 2698
Narrated Abdullah ibn AbuAwfa:
Muhammad ibn AbulMujahid reported Abdullah ibn AbuAwfa as saying: I asked: Did you set aside the fifth of the food in the time of the Apostle of Allah (peace_be_upon_him)? He replied: On the day of Khaybar we captured food and a man would come and take as much food of it as needed and then go away.