Quran 9:122 from Surah At-Tawba on Divine Marvels.
۞وَمَا كَانَ ٱلۡمُؤۡمِنُونَ لِيَنفِرُواْ كَآفَّةٗۚ فَلَوۡلَا نَفَرَ مِن كُلِّ فِرۡقَةٖ مِّنۡهُمۡ طَآئِفَةٞ لِّيَتَفَقَّهُواْ فِي ٱلدِّينِ وَلِيُنذِرُواْ قَوۡمَهُمۡ إِذَا رَجَعُوٓاْ إِلَيۡهِمۡ لَعَلَّهُمۡ يَحۡذَرُونَ
English translation: And not is (for) the believers that they go forth all together So if not go forth from every group among them a party that they may obtain understanding in the religion and that they may warn their people when they return to them so that they may beware
Transliteration: wama kana al-mu'minuna liyanfiru kaffatan falawla nafara min kulli fir'qatin min'hum taifatun liyatafaqqahu fi al-dini waliyundhiru qawmahum idha raja'u ilayhim la'allahum yahdharuna