Quran 8:67 — The Spoils of War (Al-Anfal)

No prophet shall acquire captives, unless he participates in the fighting. You people are seeking the materials of this world, while GOD advocates the Hereafter. GOD is Almighty, Most Wise.

[8:66] Now (that many new people have joined you) GOD has made it easier for you, for He knows that you are not as strong as you used to be. Henceforth, a hundred steadfast believers can defeat two hundred, and a thousand of you can defeat two thousand by GOD's leave. GOD is with those who steadfastly persevere.

[8:68] If it were not for a predetermined decree from GOD, you would have suffered, on account of what you took, a terrible retribution.