NASAI-KUBRA 4939:
from Ibn ʿUmar —
[Machine] The Messenger of Allah ﷺ said: "Whoever frees a portion for him in a person, he is obligated to free what remains. But if he does not have anything to free, then what he has done is permissible."
الكبرى للنسائي ٤٩٣٩:
عن ابن عمر —
قَالَ رَسُولُ اللهِ ﷺ «مَنْ أَعْتَقَ نَصِيبًا لَهُ فِي إِنْسَانٍ كُلِّفَ عِتْقَ مَا بَقِيَ فَإِنْ لَمْ يَكُنْ عِنْدَهُ مَا يُعْتِقُهُ جَازَ مَا صَنَعَ»