Al-Mujadila 58:3

وَٱلَّذِينَ يُظَٰهِرُونَ مِن نِّسَآئِهِمۡ ثُمَّ يَعُودُونَ لِمَا قَالُواْ فَتَحۡرِيرُ رَقَبَةٖ مِّن قَبۡلِ أَن يَتَمَآسَّاۚ ذَٰلِكُمۡ تُوعَظُونَ بِهِۦۚ وَٱللَّهُ بِمَا تَعۡمَلُونَ خَبِيرٞ 3

And those who pronounce thihar from their wives and then [wish to] go back on what they said - then [there must be] the freeing of a slave before they touch one another. That is what you are admonished thereby; and Allah is Acquainted with what you do