Musannaf Ibn Abi Shayba 19:399

Abu Bakr narrated to us, he said: Mu'adh ibn Mu'adh narrated to us, from 'Imran, from 'Ikrimah, who said: Whoever says to the son of the woman who performed li'an (imprecation), "O son of the thing," shall be lashed with the prescribed punishment (hadd).