سنن أبي داود

Narrated 'Amr b. Suh'aib:

On his father's authority, said that his grandfather reported the Prophet (ﷺ) said: When one of you marries his female servant to his slave or to his employee, he should not look at her private part below the navel and above the knees.

Abu Dawud said: The correct name is Sawwad b. Dawud al-Muzani al-Sairafi (and not Dawud b. Sawwad as mentioned in the chain). The narrator waki' misunderstood it.