{ It is not for all of the Believers to mobilize; if a small band from among each group were not to mobilize, in order to gain knowledge in religion, and make their people aware, when they return to them, that perchance they might take caution } Al-tawba 122

The Messenger of Allah (SAW), whenever He sent forth a mission after the attack on Tabuk, and after the verses of severity that were sent down concerning those who stayed behind – the Believers would try to get ahead of each other in mobilizing, and they all became disengaged from hearing the revelation and gaining knowledge in religion [deen]. So they were ordered that a small band from each group should mobilize for jihad, and those behind them should stay and gain knowledge, so that they would not become disengaged from gaining knowledge, which is the greater jihad, since debating with arguments is more effective than blows with a sword.