(35) باب مَا جَاءَ فِي الْمُكَاتَبِ إِذَا كَانَ عِنْدَهُ مَا يُؤَدِّي
Narrated 'Amr bin Shu'aib:
From his father, from his grandfather that he heard the Messenger of Allah (ﷺ) delivering a Khutbah in which he said: "Whoever gives a writ of emancipation to his slave, for one hundred Uqiyyah, and he pays it to him less then ten Uqiyah." - or he said: "Ten Dirham" - "then he becomes incapable (of paying the remainder), the he remains a slave."[Abu 'Eisa said:] This Hadith is Hasan Gharib. And this acted upon according to most of the people of knowledge among the Companions of the Prophet (ﷺ) and others: The Mukatab is a slave as long as something remains due from him for his Kitabah.Al-Hajjaj bin Artat reported similarly from 'Amr bin Shu'aib.
Reference: Jami` at-Tirmidhi 1260
In-book reference: Book 14, Hadith 62
English translation: Vol. 1, Book 12, Hadith 1260