Quran 16:93 from Surah An-Nahl on Divine Marvels.
وَلَوۡ شَآءَ ٱللَّهُ لَجَعَلَكُمۡ أُمَّةٗ وَٰحِدَةٗ وَلَٰكِن يُضِلُّ مَن يَشَآءُ وَيَهۡدِي مَن يَشَآءُۚ وَلَتُسۡـَٔلُنَّ عَمَّا كُنتُمۡ تَعۡمَلُونَ
English translation: And if Allah (had) willed Allah (had) willed surely He (could) have made you a nation one but He lets go astray whom He wills and guides whom He wills And surely you will be questioned about what you used (to) do
Transliteration: walaw shaa al-lahu laja'alakum ummatan wahidatan walakin yudillu man yashau wayahdi man yashau walatus'alunna amma kuntum ta'maluna