Surah Ash-Shura · 42:8
وَلَوْ شَاءَ اللَّهُ لَجَعَلَهُمْ أُمَّةً وَاحِدَةً وَلَٰكِنْ يُدْخِلُ مَنْ يَشَاءُ فِي رَحْمَتِهِ ۚ وَالظَّالِمُونَ مَا لَهُمْ مِنْ وَلِيٍّ وَلَا نَصِيرٍ
Now had God so willed, He could surely have made them all one single community: none the less, He admits unto His grace him that wills [to be admitted] whereas the evildoers shall have none to protect them and none to succour them [on Judgment Day].
Read Surah Ash-Shura 42:8: "Now had God so willed, He could surely have made them all one single community: none the less, He admits unto His grace ..." Full Arabic text, English translation, and image generator.