Verse 230

فَإِن طَلَّقَهَا فَلَا تَحِلُّ لَهُۥ مِنۢ بَعْدُ حَتَّىٰ تَنكِحَ زَوْجًا غَيْرَهُۥ فَإِن طَلَّقَهَا فَلَا جُنَاحَ عَلَيْهِمَآ أَن يَتَرَاجَعَآ إِن ظَنَّآ أَن يُقِيمَا حُدُودَ ٱللَّهِ وَتِلْكَ حُدُودُ ٱللَّهِ يُبَيِّنُهَا لِقَوْمٍ يَعْلَمُونَ

Then in the case of one more divorce, afterwards she is not permitted for him until she marries another husband. Thereafter, if there is a divorce, they commit no sin if they get back together, as long as they know that they are observing God’s limits. Moreover, these are God’s limits; He clarifies them for the people who are knowledgeable.