Abbad Al-Basri asked Abu Abdullah (as), while I was present with him, "How does a man invoke the mutual imprecation (li'an) against his wife?" Imam (as) replied: "A man from among the Muslims came to the Messenger of Allah (swt) (peace be upon him and his family) and said: 'O Messenger of Allah (swt), what do you say about a man who enters his house and finds another man with his wife, engaged in intercourse, what should he do about them?' The Messenger of Allah (swt) (peace be upon him and his family) turned away from him, and the man left. That man was, in fact, the one who had been afflicted with this situation concerning his wife. Then, revelation descended from Allah (swt), the Almighty, with the ruling regarding their case. The Messenger of Allah (swt) (peace be upon him and his family) sent for the man and called him. He (sw) said to him: 'Are you the one who saw a man with your wife?' He replied: 'Yes.' The Prophet (peace be upon him and his family) then said: 'Go and bring your wife to me, for Allah (swt), the Almighty, has revealed the ruling concerning you and her.'" The husband brought his wife, and the Messenger of Allah (swt) (peace be upon him and his family) had her stand before him (sw). The Prophet (peace be upon him and his family) said to the husband: "Bear witness four times by Allah (swt) that you are among the truthful in what you have accused her of." The man testified accordingly. Then the Messenger of Allah (swt) (peace be upon him and his family) said: "Pause," and He (sw) admonished him, saying, "Fear Allah (swt), for the curse of Allah (swt) is severe." He (sw) then instructed him: "Now bear witness the fifth time that the curse of Allah (swt) is upon you if you are among the liars." The man testified the fifth time. The Prophet (peace be upon him and his family) then ordered that the man be set aside and turned to the woman, saying: "Bear witness four times by Allah (swt) that your husband is among the liars in what he has accused you of." She testified accordingly. The Prophet (peace be upon him and his family) then said: "Pause," and He (sw) admonished her, saying, "Fear Allah (swt), for the anger of Allah (swt) is severe." He (sw) then told her: "Now bear witness the fifth time that the anger of Allah (swt) is upon you if your husband is among the truthful in what he has accused you of." She testified the fifth time. The Prophet (peace be upon him and his family) then separated them and said: "You two can never be joined together in marriage again after you have both engaged in liʿan."