What is the ruling on Lian when the wife is insane?
General Chapter
Al-Mughni
Book of Mutual Imprecation (Li'an)
Primary text
If the husband accuses his insane wife of adultery, he must attribute the accusation to a time when she was sane, or accuse her while sane and then break the oath (Hanith). In such cases, neither she nor her guardian can demand the Hadd before she recovers sanity, as the right to seek retribution (Qisas) is personal and cannot be exercised by a guardian for the purpose of vengeance. Upon recovery, she can demand the Hadd, which the husband may avert through Lian.
Supporting text
If the husband wishes to perform Lian while she is insane, it is not permissible because no Hadd is due to be averted, and there is no child to deny paternity. If there is a child, the established position in the Madhhab is that Lian is not performed, and the child is attributed to him. This is because Lian is only valid between two responsible spouses, and the wife cannot perform it while insane. Ahmad specified that the husband of a mute woman cannot perform Lian, making this case of insanity even more definitive.