11:118
وَلَوْ شَآءَ رَبُّكَ لَجَعَلَ ٱلنَّاسَ أُمَّةً وَٰحِدَةً ۖ وَلَا يَزَالُونَ مُخْتَلِفِينَ
walaw shāa rabbuka lajaʿala l-nāsa ummatan wāḥidatan walā yazālūna mukh'talifīna
If your Lord had pleased, He would have made all people a single community, but they continue to have their differences-
And if your Lord had so willed, He could surely have made mankind one Ummah [nation or community (following one religion i.e. Islâm)] but they will not cease to disagree.