Sura al-Nisāʾ 4:94

يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓا۟ إِذَا ضَرَبْتُمْ فِى سَبِيلِ ٱللَّـهِ فَتَبَيَّنُوا۟ وَلَا تَقُولُوا۟ لِمَنْ أَلْقَىٰٓ إِلَيْكُمُ ٱلسَّلَٰمَ لَسْتَ مُؤْمِنًا تَبْتَغُونَ عَرَضَ ٱلْحَيَوٰةِ ٱلدُّنْيَا فَعِندَ ٱللَّـهِ مَغَانِمُ كَثِيرَةٌ كَذَٰلِكَ كُنتُم مِّن قَبْلُ فَمَنَّ ٱللَّـهُ عَلَيْكُمْ فَتَبَيَّنُوٓا۟ إِنَّ ٱللَّـهَ كَانَ بِمَا تَعْمَلُونَ خَبِيرًا

yā-ayyuhā lladhīna āmanū idhā ḍarabtum fī sabīli allāhi fa-tabayyanū wa-lā taqūlū liman alqā ilaykumu l-salāma lasta muʾminan tabtaghūna ʿaraḍa l-ḥayāti l-dunyā fa-ʿinda allāhi maghānimu kathīratun ka-dhālika kuntum min qablu famanna allāhu ʿalaykum fa-tabayyanū inna allāha kāna bi-mā taʿmalūna khabīran

O ye who believe! When ye go abroad in the cause of Allah, investigate carefully, and say not to any one who offers you a salutation: "Thou art none of a believer!" Coveting the perishable goods of this life: with Allah are profits and spoils abundant. Even thus were ye yourselves before, till Allah conferred on you His favours: Therefore carefully investigate. For Allah is well aware of all that ye do.