Is the repentance of a married man who committed adultery with his wife's mother acceptable, knowing that he is remorseful and wishes to repent, suffers from a psychological illness, and regularly prays in the mosque, and should he avoid meeting his wife's mother for fear of losing his righteous wife?

One must avoid adultery, for it is an abomination. If it is with an unmarriageable kin (mahram (definition)), the perpetrator is to be killed. Scholars have differed regarding the prohibition of the wife to her husband if he commits adultery with her mother. Some view it as a prohibition, while others do not, arguing that marriage (nikah (definition)) in Islamic law refers to the one with whom a contract has been concluded, not merely to sexual intercourse, and that adultery does not render lawful things unlawful, and that the door of repentance is open for sinners.