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.  

قَالَ رَسُولُ اللَّهِ ﷺ لاَ يَجْزِي وَلَدٌ وَالِدًا إِلاَّ أَنْ يَجِدَهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيُعْتِقَهُ وَفِي رِوَايَةِ ابْنِ أَبِي شَيْبَةَ وَلَدٌ وَالِدَهُ  

the Messenger of Allah said: "A son could not do enough for his father, unless he found him as a slave and purchased him to set him free."  

قَالَ رَسُولُ اللَّهِ ﷺ لاَ يَجْزِي وَلَدٌ وَالِدًا إِلاَّ أَنْ يَجِدَهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيُعْتِقَهُ  

Messenger of Allah said: "No child can compensate his father unless he finds a slave, and buys him and sets him free."  

قَالَ رَسُولُ اللَّهِ ﷺ لاَ يَجْزِي وَلَدٌ وَالِدَهُ إِلاَّ أَنْ يَجِدَهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيُعْتِقَهُ  

A son does not repay what he owes to his father unless he buys him and emancipates him if he finds him in slavery. (Using translation from Abū Dāʾūd 5137)  

قَالَ رَسُولُ اللهِ ﷺ لَا يَجْزِي وَلَدٌ وَالِدَهُ إِلَّا أَنْ يَجِدَهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيُعْتِقَهُ  

A son does not repay what he owes to his father unless he buys him and emancipates him if he finds him in slavery. (Using translation from Abū Dāʾūd 5137)   

عَنِ النَّبِيِّ ﷺ قَالَ لَا يَجْزِي وَلَدٌ وَالِدَهُ إِلَّا أَنْ يَجِدَهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيُعْتِقَهُ  

A son does not repay what he owes to his father unless he buys him and emancipates him if he finds him in slavery. (Using translation from Abū Dāʾūd 5137)  

قَالَ رَسُولُ اللهِ ﷺ لَا يَجْزِي وَلَدٌ وَالِدَهُ إِلَّا أَنْ يَجِدَهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيُعْتِقَهُ  

A son does not repay what he owes to his father unless he buys him and emancipates him if he finds him in slavery. (Using translation from Abū Dāʾūd 5137)  

قَالَ رَسُولُ اللهِ ﷺ لَا يَجْزِي وَلَدٌ وَالِدَهُ إِلَّا أَنْ يَجِدَهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيُعْتِقَهُ  

A son does not repay what he owes to his father unless he buys him and emancipates him if he finds him in slavery. (Using translation from Abū Dāʾūd 5137)  

قَالَ رَسُولُ اللَّهِ ﷺ «لَا يَجْزِي وَلَدٌ وَالِدَهُ إِلَّا أَنْ يَجِدَهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيَعْتِقَهُ»  

A son does not repay what he owes to his father unless he buys him and emancipates him if he finds him in slavery. (Using translation from Abū Dāʾūd 5137)  

قَالَ رَسُولُ اللهِ ﷺ «لَا يَجْزِي وَلَدٌ وَالِدًا إِلَّا أَنْ يَجِدَهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيُعْتِقَهُ»  

"لَا يَجْزِي وَلَدٌ وَالدَهُ إِلَّا أنْ يَجِدهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيُعْتِقَهُ".