Al-Baqarah 2:232

وَإِذَا طَلَّقۡتُمُ ٱلنِّسَآءَ فَبَلَغۡنَ أَجَلَهُنَّ فَلَا تَعۡضُلُوهُنَّ أَن يَنكِحۡنَ أَزۡوَٰجَهُنَّ إِذَا تَرَٰضَوۡاْ بَيۡنَهُم بِٱلۡمَعۡرُوفِۗ ذَٰلِكَ يُوعَظُ بِهِۦ مَن كَانَ مِنكُمۡ يُؤۡمِنُ بِٱللَّهِ وَٱلۡيَوۡمِ ٱلۡأٓخِرِۗ ذَٰلِكُمۡ أَزۡكَىٰ لَكُمۡ وَأَطۡهَرُۚ وَٱللَّهُ يَعۡلَمُ وَأَنتُمۡ لَا تَعۡلَمُونَ 232

And when you divorce women and they have fulfilled their term, do not prevent them from remarrying their [former] husbands if they agree among themselves on an acceptable basis. That is instructed to whoever of you believes in Allah and the Last Day. That is better for you and purer, and Allah knows and you know not