Qur'an 16:93

وَلَوْ شَآءَ ٱللَّهُ لَجَعَلَكُمْ أُمَّةً وَٰحِدَةً وَلَـٰكِن يُضِلُّ مَن يَشَآءُ وَيَهْدِى مَن يَشَآءُ ۚ وَلَتُسْـَٔلُنَّ عَمَّا كُنتُمْ تَعْمَلُونَ

Had Allah willed He could have made you (all) one nation, but He sendeth whom He will astray and guideth whom He will, and ye will indeed be asked of what ye used to do.