question #3 Sahih al-Bukhari 5350, Book 68, Hadith 95 : How does Islamic law address the issue of truthfulness and false accusations in marital disputes?

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.”