"When the Prophet commanded the two who were engaging in Li'an to utter the fifth oath, he commanded a man to place his hand over his mouth, and he said: "It will inevitably bring the punishment upon the liar.""  

أَنَّ النَّبِيَّ ﷺ أَمَرَ رَجُلاً حِينَ أَمَرَ الْمُتَلاَعِنَيْنِ أَنْ يَتَلاَعَنَا أَنْ يَضَعَ يَدَهُ عِنْدَ الْخَامِسَةِ عَلَى فِيهِ وَقَالَ إِنَّهَا مُوجِبَةٌ  

When the Prophet ﷺ ordered a man and his wife to invoke curses on each other, he ordered a man to put his hand on his mouth when he came to the fifth utterance, saying that it would be the deciding one.  

أَنَّ النَّبِيَّ ﷺ أَمَرَ رَجُلاً حِينَ أَمَرَ الْمُتَلاَعِنَيْنِ أَنْ يَتَلاَعَنَا أَنْ يَضَعَ يَدَهُ عَلَى فِيهِ عِنْدَ الْخَامِسَةِ يَقُولُ إِنَّهَا مُوجِبَةٌ  

[Machine] "The Messenger of Allah ﷺ ordered a man, who was cursing between two people who were also cursing, to place his hand on his mouth at the fifth time. He said it was obligatory, and Allah, (glory be to Him), knows best."  

رَسُولَ اللهِ ﷺ أَمَرَ رَجُلًا لَاعَنَ بَيْنَ الْمُتَلَاعِنَيْنِ أَنْ يَضَعَ يَدَهُ عَلَى فِيهِ عِنْدَ الْخَامِسَةِ وَقَالَ إِنَّهَا مُوجِبَةٌ وَاللهُ سُبْحَانَهُ وَتَعَالَى أَعْلَمُ