"The Nafl is when the Imam says: 'Whoever got something, then it is his. And whoever killed a fighter, then his goods are his.' So it is allowed, and there is no Khumus taken from it." Ishaq said: "The goods are for the one who did the killing, unless it is something that is a large amount." So he saw that the Imam could take the Khumus from that, just as 'Umar bin Al-Khattab did.