What is the procedure for a husband accusing his wife of adultery without four witnesses?
General Chapter
Al-Mughni
Book of Mutual Imprecation (Li'an)
Primary text
If a husband accuses his wife of adultery and possesses no witnesses other than himself, the ruling established through the revelation concerning Hilal ibn Umayyah is that the husband must offer four testimonies (oaths) by Allah that he is among the truthful concerning his accusation. Upon the fifth oath, he must testify that the curse of Allah be upon him if he is among the liars. This process was revealed after Hilal reported finding a man with his wife, seeing it with his eyes and hearing it with his ears.
Supporting text
The wife, when accused, must also respond by testifying four oaths by Allah that the husband is among the liars. Upon the fifth oath, she has the option to testify that the wrath of Allah be upon her if the husband is truthful. In the case of Hilal, the wife hesitated to disgrace her people and made the final oath concerning the wrath of Allah.