"And it is not (proper) for the believers to go out to fight (Jihad) all together. Of every troop of them, a party only should go forth, that they (who are left behind) may get instructions in (Islamic) religion, and that they may warn their people when they return to them, so that they may beware (of evil)." - Al Quran: Juz' 9 [At Taubah: 122], Mohsin Khan translation.