'Abdullah b. 'Umar reported Allah's Messenger (ﷺ) as saying:He who gives up his share in a slave, and he has money enough to meet the full price, a fair price for him should be fixed; otherwise be has emancipated him to the extent that he has emancipated.
وَحَدَّثَنَا شَيْبَانُ بْنُ فَرُّوخَ، حَدَّثَنَا جَرِيرُ بْنُ حَازِمٍ، عَنْ نَافِعٍ، مَوْلَى عَبْدِ اللَّهِ بْنِ عُمَرَ عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنْ أَعْتَقَ نَصِيبًا لَهُ فِي عَبْدٍ فَكَانَ لَهُ مِنَ الْمَالِ قَدْرُ مَا يَبْلُغُ قِيمَتَهُ قُوِّمَ عَلَيْهِ قِيمَةَ عَدْلٍ وَإِلاَّ فَقَدْ عَتَقَ مِنْهُ مَا عَتَقَ " .
Muslim
The Book of Oaths • Hadith 74