9:111God has purchased from the believers their lives and their properties in exchange for Paradise. They fight in God’s way, and they kill and get killed. It is a promise binding on Him in the Torah, and the Gospel, and the Quran. And who is more true to his promise than God? So rejoice in making such an exchange—that is the supreme triumph.

9:122It is not advisable for the believers to march out altogether. Of every division that marches out, let a group remain behind, to gain understanding of the religion, and to notify their people when they have returned to them, that they may beware.