(1) باب فِي الْمُكَاتَبِ يُؤَدِّي بَعْضَ كِتَابَتِهِ فَيَعْجِزُ أَوْ يَمُوتُ
Narrated Umm Salamah, Ummul Mu'minin:
The Messenger of Allah (ﷺ) said to us: If one of you has a slave, and he enters into an agreement to purchase his freedom, and can pay the full price, she must veil herself from him.
Reference: Sunan Abi Dawud 3928
In-book reference: Book 31, Hadith 3
English translation: Book 30, Hadith 3917