Surat Al-Baqara (The Cow) - البقرة

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 ﴿٢٣٠﴾

So if he divorces her she shall not be lawful to him afterwards until she marries another husband; then if he divorces her there is no blame on them both if they return to each other (by marriage), if they think that they can keep within the limits of Allah, and these are the limits of Allah which He makes clear for a people who know.