وَمَا كَانَ ٱلۡمُؤۡمِنُونَ لِيَنفِرُواْ كَآفَّةً ۚ فَلَوۡلَا نَفَرَ مِن كُلِّ فِرۡقَةٍ مِّنۡهُمۡ طَآئِفَةٌ لِّيَتَفَقَّهُواْ فِى 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).<br/>
When the Prophet may peace and salutation be upon him was about to dispatch a raiding party after they [certain Muslims] had been reproached for staying behind - all of them went forth, and so the following was revealed: It is not for the believers to go forth, on a raid, altogether: why should not a party, a group, of every section, of every tribe, of them go forth, while the others remain behind, so that they, those who remain behind, may become learned in religion and that they may warn their folk when they return to them, from the raid, by teaching them some of the rulings which they have come to learn, so that they may beware? of God's punishment, by adhering to His commands and prohibitions. Ibn 'Abbaas said that this [verse] is specifically [intended] for raiding parties, while the previous one is [specifically] to prohibit any individual staying behind when the Prophet may peace and salutation be upon him sets out [on a campaign].