وَأَوۡفُواْ بِعَهۡدِ ٱللَّهِ إِذَا عَٰهَدتُّمۡ وَلَا تَنقُضُواْ ٱلۡأَيۡمَٰنَ بَعۡدَ تَوۡكِيدِهَا وَقَدۡ جَعَلۡتُمُ ٱللَّهَ عَلَيۡكُمۡ كَفِيلًاۚ إِنَّ ٱللَّهَ يَعۡلَمُ مَا تَفۡعَلُونَ
And fulfill the Covenant of Allah (Bai'a: pledge for Islam) when you have covenanted, and break not the oaths after you have confirmed them, and indeed you have appointed Allah your surety. Verily! Allah knows what you do.
وَلَا تَكُونُواْ كَٱلَّتِي نَقَضَتۡ غَزۡلَهَا مِنۢ بَعۡدِ قُوَّةٍ أَنكَٰثٗا تَتَّخِذُونَ أَيۡمَٰنَكُمۡ دَخَلَۢا بَيۡنَكُمۡ أَن تَكُونَ أُمَّةٌ هِيَ أَرۡبَىٰ مِنۡ أُمَّةٍۚ إِنَّمَا يَبۡلُوكُمُ ٱللَّهُ بِهِۦۚ وَلَيُبَيِّنَنَّ لَكُمۡ يَوۡمَ ٱلۡقِيَٰمَةِ مَا كُنتُمۡ فِيهِ تَخۡتَلِفُونَ
And be not like her who undoes the thread which she has spun after it has become strong, by taking your oaths a means of deception among yourselves, lest a nation may be more numerous than another nation. Allah only tests you by this [i.e. who obeys Allah and fulfills Allah's Covenant and who disobeys Allah and breaks Allah's Covenant]. And on the Day of Resurrection, He will certainly make clear to you that wherein you used to differ [i.e. a believer confesses and believes in the Oneness of Allah and in the Prophethood of Prophet Muhammad SAW which the disbeliever denies it and that was their difference amongst them in the life of this world].
وَلَوۡ شَآءَ ٱللَّهُ لَجَعَلَكُمۡ أُمَّةٗ وَٰحِدَةٗ وَلَٰكِن يُضِلُّ مَن يَشَآءُ وَيَهۡدِي مَن يَشَآءُۚ وَلَتُسۡـَٔلُنَّ عَمَّا كُنتُمۡ تَعۡمَلُونَ
And had Allah willed, He could have made you (all) one nation, but He sends astray whom He wills and guides whom He wills. But you shall certainly be called to account for what you used to do.