Another narration in Muslim is: "The Messenger of Allah (PBUH) prohibited us from hitting across the face and branding on the face (of an animal)."
Commentary: Since face is the most sensitive and delicate part of the body, Muslims are strictly forbidden from causing even the slightest harm to it, no matter whether it is mankind or animal. Although, it is permissible to beat one's wife, children and slaves etc., for discipline but there is a stern warning that they should not be hit on the face.