Al-Kāfi - Volume 7 > The Guardianship of One who Sets One Free
Hadith #4

4- صَفْوَانُ عَنِ الْعِيصِ بْنِ الْقَاسِمِ عَنْ أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) قَالَ سَأَلْتُهُ عَنْ رَجُلٍ اشْتَرَى عَبْداً لَهُ أَوْلادٌ مِنِ امْرَأَةٍ حُرَّةٍ فَأَعْتَقَهُ قَالَ وَلاءُ وُلْدِهِ لِمَنْ أَعْتَقَهُ.

4. Safwan has narrated from al-‘Is ibn al-Qasim ibn Muhammad who has narrated the following: “I once asked abu ‘Abd Allah, ‘Alayhi al-Salam, about the case of a man who buys a slave who has children from a free woman who has set him free. He (the Imam) said, ‘The guardianship of his children rests with one who has bought his freedom.’”