58:2
ٱلَّذِينَ يُظَـٰهِرُونَ مِنكُم مِّن نِّسَآئِهِم مَّا هُنَّ أُمَّهَـٰتِهِمْ ۖ إِنْ أُمَّهَـٰتُهُمْ إِلَّا ٱلَّـٰٓـِٔى وَلَدْنَهُمْ ۚ وَإِنَّهُمْ لَيَقُولُونَ مُنكَرًا مِّنَ ٱلْقَوْلِ وَزُورًا ۚ وَإِنَّ ٱللَّهَ لَعَفُوٌّ غَفُورٌ
Those who pronounce thihar among you [to separate] from their wives - they are not [consequently] their mothers. Their mothers are none but those who gave birth to them. And indeed, they are saying an objectionable statement and a falsehood. But indeed, Allah is Pardoning and Forgiving.
Context in Surah Al-Mujadila
Nearby ayahs help place verse 58:2 in sequence and meaning.
قَدْ سَمِعَ ٱللَّهُ قَوْلَ ٱلَّتِى تُجَـٰدِلُكَ فِى زَوْجِهَا وَتَشْتَكِىٓ إِلَى ٱللَّهِ وَٱللَّهُ يَسْمَعُ تَحَاوُرَكُمَآ ۚ إِنَّ ٱللَّهَ سَمِيعٌۢ بَصِيرٌ
Certainly has Allah heard the speech of the one who argues with you, [O Muhammad], concerning her husband and directs her complaint to Allah. And Allah hears your dialogue; indeed, Allah is Hearing and Seeing.
وَٱلَّذِينَ يُظَـٰهِرُونَ مِن نِّسَآئِهِمْ ثُمَّ يَعُودُونَ لِمَا قَالُوا۟ فَتَحْرِيرُ رَقَبَةٍ مِّن قَبْلِ أَن يَتَمَآسَّا ۚ ذَٰلِكُمْ تُوعَظُونَ بِهِۦ ۚ وَٱللَّهُ بِمَا تَعْمَلُونَ خَبِيرٌ
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.
فَمَن لَّمْ يَجِدْ فَصِيَامُ شَهْرَيْنِ مُتَتَابِعَيْنِ مِن قَبْلِ أَن يَتَمَآسَّا ۖ فَمَن لَّمْ يَسْتَطِعْ فَإِطْعَامُ سِتِّينَ مِسْكِينًا ۚ ذَٰلِكَ لِتُؤْمِنُوا۟ بِٱللَّهِ وَرَسُولِهِۦ ۚ وَتِلْكَ حُدُودُ ٱللَّهِ ۗ وَلِلْكَـٰفِرِينَ عَذَابٌ أَلِيمٌ
And he who does not find [a slave] - then a fast for two months consecutively before they touch one another; and he who is unable - then the feeding of sixty poor persons. That is for you to believe [completely] in Allah and His Messenger; and those are the limits [set by] Allah. And for the disbelievers is a painful punishment.