(1) باب فِي الْمُكَاتَبِ يُؤَدِّي بَعْضَ كِتَابَتِهِ فَيَعْجِزُ أَوْ يَمُوتُ
Narrated 'Amr b. Shu'aib:
on his father's authority, told that his grandfather reported the Prophet (ﷺ) said: A slave who has entered into an agreement to purchase his freedom is a slave as long as a dirham of the agreed price remains to be paid.
Reference: Sunan Abi Dawud 3926
In-book reference: Book 31, Hadith 1
English translation: Book 30, Hadith 3915