The Prophet ﷺ said, "Whoever manumits a slave owned by two masters, should manumit him completely (not partially) if he is rich after having its price evaluated."
عَنِ النَّبِيِّ ﷺ قَالَ مَنْ أَعْتَقَ عَبْدًا بَيْنَ اثْنَيْنِ فَإِنْ كَانَ مُوسِرًا قُوِّمَ عَلَيْهِ ثُمَّ يُعْتَقُ
If a man is shared by two men, and one of them emancipates his share, a price of the slave will be fixed, not more or less, and he will be emancipated by him in case he is rich.
النَّبِيَّ ﷺ إِذَا كَانَ الْعَبْدُ بَيْنَ اثْنَيْنِ فَأَعْتَقَ أَحَدُهُمَا نَصِيبَهُ فَإِنْ كَانَ مُوسِرًا يُقَوَّمُ عَلَيْهِ قِيمَةً لاَ وَكْسَ وَلاَ شَطَطَ ثُمَّ يُعْتَقُ
If a man is shared by two men, and one of them emancipates his share, a price of the slave will be fixed, not more or less, and he will be emancipated by him in case he is rich. (Using translation from Abū Dāʾūd 3947)
النَّبِيَّ ﷺ إِذَا كَانَ الْعَبْدُ بَيْنَ اثْنَيْنِ فَأَعْتَقَ أَحَدُهُمَا نَصِيبَهُ فَإِنْ كَانَ مُوسِرًا قُوِّمَ عَلَيْهِ قِيمَةً لَا وَكْسَ وَلَا شَطَطَ ثُمَّ يُعْتَقُ