On his father's authority, said that his grandfather reported the Prophet (ﷺ) said: When one of you marries his male-slave to his slave-woman, he should not look at her private parts.
Sunan Abi Dawud Book 34, Hadith 94
← Previous Hadith I was with the Messenger of Allah (ﷺ) while Maymunah was with him. Then Ibn Umm Maktum came. This happened when we were ordered to observe veil (purdah). The Prophet (ﷺ) said: Observe veil from him. We asked: Messenger of Allah! is he not blind? He can neither see us nor recognise us. The Prophet (ﷺ) said: Are both of you blind? Do you not see him? AbuDawud said: This was peculiar to the wives of the Prophet (ﷺ). Do you not see that Fatimah daughter of Qays passed her waiting period with Ibn Umm Maktum. The Prophet (ﷺ) said to Fatimah daughter of Qays: Pass your waiting period with Ibn Umm Maktum, for he is a blind man. You can put off your clothes with him.

Sunan Abi Dawud Book 34, Hadith 93 Next Hadith → 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.

Sunan Abi Dawud Book 34, Hadith 95