No Prophet is entitled to take prisoners of war under the circumstances when the infidels are doing their best to defy Allah's religion, until he has humbled the avowed enemies of faith and subdued the land at the peril of their lives. To take prisoners and ransom them at this stage means that you Muslims are concerned with the interests and pleasures of this life when Allah's concern is the Hereafter, and Allah is Azizun and Hakimun.