"And the fifth (testimony should be) the invoking of the Curse of Allah on him if he is of those who tell a lie (against her) ." (V.24:7)

Sahih al-Bukhari · Book 65 · Hadith 4746

حَدَّثَنِي سُلَيْمَانُ بْنُ دَاوُدَ أَبُو الرَّبِيعِ، حَدَّثَنَا فُلَيْحٌ، عَنِ الزُّهْرِيِّ، عَنْ سَهْلِ بْنِ سَعْدٍ، أَنَّ رَجُلاً، أَتَى رَسُولَ اللَّهِ صلى الله عليه وسلم فَقَالَ يَا رَسُولَ اللَّهِ، أَرَأَيْتَ رَجُلاً رَأَى مَعَ امْرَأَتِهِ رَجُلاً أَيَقْتُلُهُ فَتَقْتُلُونَهُ أَمْ كَيْفَ يَفْعَلُ فَأَنْزَلَ اللَّهُ فِيهِمَا مَا ذُكِرَ فِي الْقُرْآنِ مِ…

Narrated Sahl bin Sa`d: A man came to Allah's Messenger (ﷺ) and said, "O Allah's Messenger! Suppose a man saw another man with his wife, should he kill him whereupon you might kill him (i.e. the killer) (in Qisas) or wh…