And 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.
And it is not for the believers to go forth [to battle] all at once. For there should separate from every division of them a group [remaining] to obtain understanding in the religion and warn their people when they return to them that they might be cautious.
Nor should the Believers all go forth together: if a contingent from every expedition remained behind, they could devote themselves to studies in religion, and admonish the people when they return to them,- that thus they (may learn) to guard themselves (against evil).