كتاب العتق
20  
The Book of Emancipating Slaves
(7)
Chapter: The virtue of manumitting one's father
(7)
باب فَضْلِ عِتْقِ الْوَالِدِ ‏‏
Sahih Muslim 1510 a

Abu Huraira (Allah be pleased with him) reported Allah's Messenger (ﷺ) as saying:

A son does not repay what he owes his father unless he buys him (the father) in case he is a slave and then emancipates him. In the narration transmitted by Ibn Abu Shaiba there is a slight change of words.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَزُهَيْرُ بْنُ حَرْبٍ، قَالاَ حَدَّثَنَا جَرِيرٌ، عَنْ سُهَيْلٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ لاَ يَجْزِي وَلَدٌ وَالِدًا إِلاَّ أَنْ يَجِدَهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيُعْتِقَهُ ‏"‏ ‏.‏ وَفِي رِوَايَةِ ابْنِ أَبِي شَيْبَةَ ‏"‏ وَلَدٌ وَالِدَهُ ‏"‏ ‏.‏
Reference : Sahih Muslim 1510a
In-book reference : Book 20, Hadith 29
USC-MSA web (English) reference : Book 9, Hadith 3606
  (deprecated numbering scheme)