Allah says in the Quran:

وَاَعْتَصِمُواْ بِحَبْلِ اللَّهِ جَمِيعًا وَلا تَفَرَّقُوأْ وَاذكُرُواْ نِعْمَتَ اللهِ عَلَيْكُمْ إِذْ كُنتُمْ أَعْدَاءً فَأَلَّفَ بَيْنَ قُلُوبِكُمْ فَأَصبَحْتُم بِنِعْمَتِهِ، إِخْوَنًا وَكُنتُمْ عَلَى شَفَا حُفَرَةٍ مِّنَ الِنَّارٍ فَأَنقَذَكُمٍ مِّنَّهَأُ كَذَّلِكَ يُبَيِّنُ اللهُ لَكُمْ ءَايَتِهِ لَعَلَّكُمْ تَهْتَدُونَ

And hold fast, all of you together, to the Rope of Allah (i.e. this Qur’an), and be not divided among yourselves, and remember Allah’s Favour on you, for you were enemies one to another but He joined your hearts together, so that, by His Grace, you became brethren (in Islamic Faith), and you were on the brink of a pit of Fire, and He saved you from it. Thus Allah makes His Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.,) clear to you, that you may be guided. [3:103]