فَإِن طَلَّقَهَا فَلَا تَحِلُّ لَهُۥ مِنۢ بَعۡدُ حَتَّىٰ تَنكِحَ زَوۡجًا غَيۡرَهُۥۗ فَإِن طَلَّقَهَا فَلَا جُنَاحَ عَلَيۡهِمَآ أَن يَتَرَاجَعَآ إِن ظَنَّآ أَن يُقِيمَا حُدُودَ ٱللَّهِۗ وَتِلۡكَ حُدُودُ ٱللَّهِ يُبَيِّنُهَا لِقَوۡمٖ يَعۡلَمُونَ
So if a husband divorces his wife (irrevocably), He cannot, after that, re-marry her until after she has married another husband and He has divorced her. In that case there is no blame on either of them if they re-unite, provided they feel that they can keep the limits ordained by Allah. Such are the limits ordained by Allah, which He makes plain to those who understand.
وَإِذَا طَلَّقۡتُمُ ٱلنِّسَآءَ فَبَلَغۡنَ أَجَلَهُنَّ فَأَمۡسِكُوهُنَّ بِمَعۡرُوفٍ أَوۡ سَرِّحُوهُنَّ بِمَعۡرُوفٖۚ وَلَا تُمۡسِكُوهُنَّ ضِرَارٗا لِّتَعۡتَدُواْۚ وَمَن يَفۡعَلۡ ذَٰلِكَ فَقَدۡ ظَلَمَ نَفۡسَهُۥۚ وَلَا تَتَّخِذُوٓاْ ءَايَٰتِ ٱللَّهِ هُزُوٗاۚ وَٱذۡكُرُواْ نِعۡمَتَ ٱللَّهِ عَلَيۡكُمۡ وَمَآ أَنزَلَ عَلَيۡكُم مِّنَ ٱلۡكِتَٰبِ وَٱلۡحِكۡمَةِ يَعِظُكُم بِهِۦۚ وَٱتَّقُواْ ٱللَّهَ وَٱعۡلَمُوٓاْ أَنَّ ٱللَّهَ بِكُلِّ شَيۡءٍ عَلِيمٞ
When ye divorce women, and they fulfil the term of their ('Iddat), either take them back on equitable terms or set them free on equitable terms; but do not take them back to injure them, (or) to take undue advantage; if any one does that; He wrongs his own soul. Do not treat Allah's Signs as a jest, but solemnly rehearse Allah's favours on you, and the fact that He sent down to you the Book and Wisdom, for your instruction. And fear Allah, and know that Allah is well acquainted with all things.