He said that the Prophet ﷺ, when he commanded the Mutalaineen to perform the mutual oath of condemnation, instructed a man to place his hand over the man's mouth at the fifth oath, saying, "It is the one that brings the punishment down upon him."
قال أن النبي ﷺ أمر رجلا حين أمر المتلاعنين أن يتلاعن: أن يضع يده على فيه عند الخامسة يقول: إنها موجبة.
Narrated by Abu Dawud (2255), Nasai (3472), and Bayhaqi (7/405), all through the hadith of Sufyan, from Asim bin Kulayb, from his father, from Ibn Abbas, who related it.Its chain is hasan because of Asim bin Kulayb, for his hadith is hasan. Likewise his father, Kulayb bin Shihab Jarmi. It has not been established in the sunnahs that a hand was placed over the woman's mouth.