O you who believe! when you set forth in the cause of Allâh, then make proper investigations (before you dub anyone as a disbeliever), and do not say to him who offers you `Salâm', (- peace, the Muslim salutation to show himself thereby a Muslim,) `You are not a believer.' You seek the transitory goods of this life, but Allâh has good things in plenty with Him. You were such (disbelievers) before that (you accepted Islam), but Allâh has conferred His special favour on you, hence do make proper investigations. Surely, Allâh is Well-Aware of what you do.