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. (Using translation from Abū Dāʾūd 2255)  

أَنَّ النَّبِيَّ ﷺ أَمَرَ رَجُلًا حِينَ أَمَرَ الْمُتَلَاعِنَيْنِ أَنْ يَتَلَاعَنَا أَنْ يَضَعَ يَدَهُ عِنْدَ الْخَامِسَةِ عَلَى فِيهِ وَقَالَ «إِنَّهَا مُوجِبَةٌ»