Surah Yunus, ayah 19

وَمَا كَانَ ٱلنَّاسُ إِلَّآ أُمَّةٗ وَٰحِدَةٗ فَٱخۡتَلَفُواْۚ وَلَوۡلَا كَلِمَةٞ سَبَقَتۡ مِن رَّبِّكَ لَقُضِيَ بَيۡنَهُمۡ فِيمَا فِيهِ يَخۡتَلِفُونَ ١٩

Wamā kānan-nāsu illā ummatan wāhidatan fakhtalafū walawlā kalimatun sabaqat mir rabbika laqudiya baynahum fīmā fīhi yakhtalifūn

And mankind was not but one community [united in religion], but [then] they differed. And if not for a word⁵¹⁷ that preceded from your Lord, it would have been judged between them [immediately] concerning that over which they differ.