Sahih Bukhari
One-fifth of Booty to the Cause of Allah (Khumus)
Volume: 004 / Book Number: 053 / Hadith Number: 367
Narrated Jubair bin Mutim:
The Prophet talked about war prisoners of Badr saying, "Had Al-Mutim bin Adi been alive and interceded with me for these mean people, I would have freed them for his sake."