Man Lā Yaḥḍuruh al-Faqīh
Hadith 633483 - وَ رَوَى حَمَّادٌ عَنِ اَلْحَلَبِيِّ عَنْ أَبِي عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ : فِي اَلْمُكَاتَبِ يُكَاتَبُ وَ يَشْتَرِطُ عَلَيْهِ مَوَالِيهِ أَنَّهُ إِنْ عَجَزَ فَهُوَ مَمْلُوكٌ وَ لَهُمْ مَا أَخَذُوا مِنْهُ قَالَ "يَأْخُذُهُ مَوَالِيهِ بِشَرْطِهِمْ".
Hadith.3483 - Hammad narrated from al-Halabi, from Abu Abdullah (as), regarding a mukatab (a slave under a contract of emancipation) who enters into the contract with his masters, and they stipulate that if he fails to complete the payments, he will return to slavery, and whatever they have already received from him will remain theirs.
Imam (as) said: "His masters will take him back as a slave based on their condition."