Sayyiduna Sa'id bin Jubair says that during the caliphate of Mus'ab bin Zubair, I was asked about the issue of those who perform li'an (mutual cursing), so I was surprised as to what answer I should give. So I went towards the house of Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) which was located in Makkah, and I said to his servant to convey my request. He said that he (Abdullah bin Umar, may Allah be pleased with them both) is resting. He heard my voice and said, "Is it the son of Jubair?" I said, "Yes." He said, "Come inside. By Allah, you must have come for some purpose." I went inside and he was sitting on a spread blanket and reclining on a pillow filled with date palm fibers. I said, "O Abu Abdur Rahman! Should separation be made between those who perform li'an?" He said, "Subhan Allah! Indeed, separation will be made. And the first to ask about this matter from the Messenger of Allah (peace and blessings be upon him) was so-and-so, who was the son of so-and-so. He said, 'O Messenger of Allah! What do you think, if any one of us sees his wife committing an evil act, what should he do? If he speaks out, it is a grave matter, and if he remains silent, how can he remain silent over such a grave matter?' The Messenger of Allah (peace and blessings be upon him) remained silent upon hearing this and did not reply. Then that person came to you (peace and blessings be upon him) and said, 'O Messenger of Allah! The matter I asked you about, I myself have fallen into it.' Then Allah Almighty revealed these verses in Surah An-Nur: 'And those who accuse their wives...' till the end. The Prophet (peace and blessings be upon him) recited these verses to him and advised him and explained that the punishment of this world is easier than the punishment of the Hereafter (meaning, if you are fabricating a lie, then even now confess, and you will receive the punishment of eighty lashes for false accusation, but this is easier than burning in Hell). He said, 'By the One Who sent you with the truth, I have not fabricated a lie against my wife.' Then the Prophet (peace and blessings be upon him) called the woman and warned and advised her and said, 'The punishment of this world is easier than the punishment of the Hereafter.' She said, 'By the One Who sent you with the truth, my husband is lying.' Then the Prophet (peace and blessings be upon him) started with the man, and he gave four testimonies in the name of Allah that he is surely truthful, and the fifth time he said, 'May the curse of Allah be upon him if he is lying.' Then the woman was called, and she gave four testimonies in the name of Allah that the man is lying, and the fifth time she said, 'May the wrath of Allah be upon her if the man is truthful.' After that, the Prophet (peace and blessings be upon him) separated the two of them.