﴿ وَٱعْتَصِمُوا۟ بِحَبْلِ ٱللَّهِ جَمِيعًۭا وَلَا تَفَرَّقُوا۟ ۚ وَٱذْكُرُوا۟ نِعْمَتَ ٱللَّهِ عَلَيْكُمْ إِذْ كُنتُمْ أَعْدَآءًۭ فَأَلَّفَ بَيْنَ قُلُوبِكُمْ فَأَصْبَحْتُم بِنِعْمَتِهِۦٓ إِخْوَٰنًۭا وَكُنتُمْ عَلَىٰ شَفَا حُفْرَةٍۢ مِّنَ ٱلنَّارِ فَأَنقَذَكُم مِّنْهَا ۗ كَذَٰلِكَ يُبَيِّنُ ٱللَّهُ لَكُمْ ءَايَٰتِهِۦ لَعَلَّكُمْ تَهْتَدُونَ ﴾

“And hold fast, all together, unto the bond with God, and do not draw apart from one another. And remember the blessings which God has bestowed upon you: how, when you were enemies, He brought your hearts together, so that through His blessing you became brethren; and [how, when] you were on the brink of a fiery abyss. He saved you from it. In this way God makes clear His messages unto you, so that you might find guidance,”

Before the advent of Islam there were two tribes, the Aws and Khazraj, inhabiting Madinah. Both were Arabs, but they continuously waged war against each other. Attacks and counter-attacks had considerably weakened them. When they accepted Islam, all hostilities ended: they became like brothers. The reason for this is that one who denies the truth is faithful only to his own self, while a believer gives his allegiance solely to God. In a society where individuals are faithful only to their own selves or to their groups, many allegiances naturally come into existence. The result is strife and dissension. On the contrary, in a society where all its members bow only to one God, everyone is directed towards a single focal point. All being bound by one and the same cord, mutual clashes and strife cease altogether.