Sunan Abu Dawud
2255
Sahih+2

Narrated Abdullah ibn Abbas: 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

SahihAl-Albani
SahihMuhammad Muhyi Al-Din Abdul Hamid