At Tawbah Ayah 122

۞ وَمَا كَانَ ٱلْمُؤْمِنُونَ لِيَنفِرُواْ كَآفَّةً‌ۚ فَلَوْلَا نَفَرَ مِن كُلِّ فِرْقَةٍ مِّنْهُمْ طَآئِفَةٌ لِّيَتَفَقَّهُواْ فِى ٱلدِّينِ وَلِيُنذِرُواْ قَوْمَهُمْ إِذَا رَجَعُوٓاْ إِلَيْهِمْ لَعَلَّهُمْ يَحْذَرُونَ ١٢٢ ?However,? it is not necessary for the believers to march forth all at once. Only a party from each group should march forth, leaving the rest to gain religious knowledge then enlighten their people when they return to them, so that they ?too? may beware ?of evil?.