التَّوْبَةِ · 122

۞وَمَا كَانَ ٱلۡمُؤۡمِنُونَ لِيَنفِرُواْ كَآفَّةࣰۚ فَلَوۡلَا نَفَرَ مِن كُلِّ فِرۡقَةࣲ مِّنۡهُمۡ طَآئِفَةࣱ لِّيَتَفَقَّهُواْ فِي ٱلدِّينِ وَلِيُنذِرُواْ قَوۡمَهُمۡ إِذَا رَجَعُوٓاْ إِلَيۡهِمۡ لَعَلَّهُمۡ يَحۡذَرُونَ

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)