Sunan an-Nasa'i 3472
سنن النسائي#3472Sahihأَخْبَرَنَا عَلِيُّ بْنُ مَيْمُونٍ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ عَاصِمِ بْنِ كُلَيْبٍ، عَنْ أَبِيهِ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم أَمَرَ رَجُلاً حِينَ أَمَرَ الْمُتَلاَعِنَيْنِ أَنْ يَتَلاَعَنَا أَنْ يَضَعَ يَدَهُ عِنْدَ الْخَامِسَةِ عَلَى فِيهِ وَقَالَ " إِنَّهَا مُوجِبَةٌ " .
It was narrated from Ibn 'Abbas:"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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih
In-book reference: 27:84