Narrated Ibn 'Umar:

The Prophet ﷺ said to those who were involved in a case of Lian, "Your accounts are with Allah. One of you two is a liar. You (husband) have right on her (wife)." The husband said, "My money, O Allah's Apostle!" The Prophet ﷺ said, "You are not entitled to take back any money. If you have told the truth, the Mahr that you paid, was for having sexual relations with her lawfully;
and if you are a liar, then you are less entitled to get it back."

حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا سُفْيَانُ، عَنْ عَمْرٍو، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عُمَرَ، أَنَّ النَّبِيَّ ﷺ قَالَ لِلْمُتَلاَعِنَيْنِ " حِسَابُكُمَا عَلَى اللَّهِ، أَحَدُكُمَا كَاذِبٌ، لاَ سَبِيلَ لَكَ عَلَيْهَا ". قَالَ يَا رَسُولَ اللَّهِ مَالِي. قَالَ " لاَ مَالَ لَكَ، إِنْ كُنْتَ صَدَقْتَ عَلَيْهَا، فَهْوَ بِمَا اسْتَحْلَلْتَ مِنْ فَرْجِهَا، وَإِنْ كُنْتَ كَذَبْتَ عَلَيْهَا، فَذَاكَ أَبْعَدُ وَأَبْعَدُ لَكَ مِنْهَا ".