It is not fitting for a prophet that he should have prisoners of war until he hath thoroughly subdued the land. Ye look for the temporal goods of this world; but Allah looketh to the Hereafter: And Allah is Exalted in might, Wise.
Yusuf Ali writes,
An ordinary war may be for territory or trade,
revenge or military glory, -all “temporal goods of this
Such a war is condemned. But a Jihad is fought under
strict conditions laid down by Islam, and solely for the
cause of Allah. All baser motives, therefore are strictly
excluded. The greed of gain in the shape of ransom from
captives has no place in such warfare. (R).
At the same time, if there has been heavy loss of life
already, captives may be taken, and it would be for the
Imam to exercise his discretion as to the time when it
was safe to release them, and whether the release
should be free or on parole or on a fine by way of
Destruction and slaughter, however repugnant to a
gentle soul like that of Muhammad, were inevitable
where evil tried to suppress the good. Even Jesus, whose
mission was more limited, had to say: “Think not that I
am come to send peace on earth: I came not to send
peace but a sword.” (Matt. 10:34).
Seventy captives were taken at Badr, and it was decided
to take ransom for them. While the general principle of
fighting for the purpose of taking captives in order to get
their ransom is condemned, the particular action in this
case was approved in verses 68-71.
Yusuf Ali, Abdullah. Translation and Commentary of the Quran. (surah 8 verse 67). Microsoft Word – 008 Anfal.doc (quran4u.com)