Sura al-Mujādilah 58:3

وَٱلَّذِينَ يُظَٰهِرُونَ مِن نِّسَآئِهِمْ ثُمَّ يَعُودُونَ لِمَا قَالُوا۟ فَتَحْرِيرُ رَقَبَةٍ مِّن قَبْلِ أَن يَتَمَآسَّا ذَٰلِكُمْ تُوعَظُونَ بِهِۦ وَٱللَّـهُ بِمَا تَعْمَلُونَ خَبِيرٌ

wa-lladhīna yuẓāhirūna min nisāʾihim thumma yaʿūdūna li-mā qālū fa-taḥrīru raqabatin min qabli an yatamāssā dhālikum tūʿaẓūna bihi wallāhu bi-mā taʿmalūna khabīrun

But those who divorce their wives by Zihar, then wish to go back on the words they uttered,- (It is ordained that such a one) should free a slave before they touch each other: Thus are ye admonished to perform: and Allah is well-acquainted with (all) that ye do.