She reported that the Prophet ﷺ said, "If any of you has a slave under a contract of manumission and he possesses enough to pay off his contract, she should observe veiling from him."
حدثنا أبو بكر بن أبي شيبة حدثنا سفيان بن عيينة عن الزهري عن نبهان مولى أم سلمة
أنها أخبرت عن النبي ﷺ أنه قال إذا كان لإحداكن مكاتب وكان عنده ما يؤدي فلتحتجب منه
Its chain is hasan. Abu Dawud narrated it in the Book of Emancipation, chapter on the mukatab who pays part of his contract then defaults or dies, hadith 3928, from the narration of Sufyan bin Uyayna, with this wording. Tirmidhi graded it sahih, hadith 1261, as did Ibn Hibban, and Hakim, 2/219, and Dhahabi.I say, Nabhan was deemed reliable by Dhahabi in Kashif, and by Tirmidhi, Ibn Hibban, and the majority, so his hadith does not fall below the rank of hasan. Zuhri explicitly stated that he heard it directly.