Going forth into Battle
Yet it is not necessary for all believers to march forth. Why not have some stay behind to gain deeper knowledge of religion and warn their people when they return, so they may be mindful?
9:122And the believers should not all go out to fight. Of every troop of them, a party only should go forth, that they (who are left behind) may gain sound knowledge in religion, and that they may warn their folk when they return to them, so that they may beware.