Musannaf Ibn Abi Shayba 19:391

Abu Bakr narrated to us, he said: Abbad ibn al-Awwam narrated to us, from Umar ibn Amir, from Hammad, from Ibrahim, who said: If a man declares himself a liar before anything of her *li'an* (oath of imprecation) remains, he is flogged, and she remains his wife.