Musannaf Ibn Abi Shayba 7:252

Ibn al-Mubarak narrated to us, from Abu Hanifah, from Hammad, from Ibrahim, regarding the *muẓāhir* (one who performs *ẓihār*): He should perform the *kaffārah* (expiation) at the end of the night or the day. He said: He should begin the fasting.