Surat Yūnus - سورة يونس

وَمَا كَانَ النَّاسُ إِلَّا أُمَّةً وَاحِدَةً فَاخْتَلَفُوا ۚ وَلَوْلَا كَلِمَةٌ سَبَقَتْ مِن رَّبِّكَ لَقُضِيَ بَيْنَهُمْ فِيمَا فِيهِ يَخْتَلِفُونَ

Muhsin Khan: Mankind were but one community (i.e. on one religion - Islamic Monotheism), then they differed (later), and had not it been for a Word that went forth before from your Lord, it would have been settled between them regarding what they differed.