Hilal bin Yasaf said: We were staying in the house of Suwaid bin Muqarrin. There was among us an old man who was hot-tempered. He had a slave-girl with him. He gave a slap on her face. I never saw Suwaid more angry than on that day. He said: there is no alternative for you except to free her. I was the seventh child in order of Muqarrin and we had only a female servant. The youngest of us gave a slap on her face. The prophet ﷺ commanded us to set her free.
Hadith Referenceسنن ابي داود / أبواب النوم / 5166
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:صحيح مسلم (1658),
Benefits and Issues: Striking the face is strictly prohibited. And the Messenger of Allah (sallallahu alayhi wa sallam) has forbidden this. His (sallallahu alayhi wa sallam) noble statement is: (“If one of you fights his brother, let him avoid the face.”) (Sahih Muslim, Al-Birr wa al-Silah, Hadith: 2612) When any of you has a fight with his (Muslim) brother, he should avoid (striking) his face. Even the face of an animal should not be struck.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 5166