The people used to be one congregation, then they disputed. If it were not for a predetermined word from your Lord, they would have been judged immediately regarding their disputes.
وَما كانَ النّاسُ إِلّا أُمَّةً وٰحِدَةً فَاختَلَفوا وَلَولا كَلِمَةٌ سَبَقَت مِن رَبِّكَ لَقُضِىَ بَينَهُم فيما فيهِ يَختَلِفونَ
wa maa kaanan naasu illaaa ummatanw waahidatan fa khtalafoo; wa law laa kalimatun sabaqat mir Rabbika laqudiya bainahum fee maa feehi yakhtalifoon