An-Nisa 4:94

يَـٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓا۟ إِذَا ضَرَبْتُمْ فِى سَبِيلِ ٱللَّهِ فَتَبَيَّنُوا۟ وَلَا تَقُولُوا۟ لِمَنْ أَلْقَىٰٓ إِلَيْكُمُ ٱلسَّلَـٰمَ لَسْتَ مُؤْمِنًا تَبْتَغُونَ عَرَضَ ٱلْحَيَوٰةِ ٱلدُّنْيَا فَعِندَ ٱللَّهِ مَغَانِمُ كَثِيرَةٌ ۚ كَذَٰلِكَ كُنتُم مِّن قَبْلُ فَمَنَّ ٱللَّهُ عَلَيْكُمْ فَتَبَيَّنُوٓا۟ ۚ إِنَّ ٱللَّهَ كَانَ بِمَا تَعْمَلُونَ خَبِيرًا

Yāayyuhā alladhīna āmanū idhā ḍarabtum fī sabīli l-lahi fatabayyanū walā taqūlū liman alqā ilaykumu l-salāma lasta mu'minan tabtaghūna ʿaraḍa l-ḥayati l-dun'yā faʿinda l-lahi maghānimu kathīratun kadhālika kuntum min qablu famanna l-lahu ʿalaykum fatabayyanū inna l-laha kāna bimā taʿmalūna khabīran

O you who have believed, when you go forth [to fight] in the cause of Allāh, investigate; and do not say to one who gives you [a greeting of] peace, "You are not a believer," aspiring for the goods of worldly life; for with Allāh are many acquisitions. You [yourselves] were like that before; then Allāh conferred His favor [i.e., guidance] upon you, so investigate. Indeed Allāh is ever, of what you do, Aware.