Sahih Muslim 1501 g
Salim b. 'Abdullah reported on the authority of his father that Allah's Apostle (ﷺ) said:
He who emancipates a slave (shared) by him and another one, his full price may be justly assessed from his wealth, neither less nor more, and he (the slave) would be emancipated if he (the partner) would be solvent enough (to forgo the amount of his share).
وَحَدَّثَنَا عَمْرٌو النَّاقِدُ، وَابْنُ أَبِي عُمَرَ، كِلاَهُمَا عَنِ ابْنِ عُيَيْنَةَ، قَالَ ابْنُ أَبِي عُمَرَ حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنْ عَمْرٍو، عَنْ سَالِمِ بْنِ عَبْدِ اللَّهِ، عَنْ أَبِيهِ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏
"‏ مَنْ أَعْتَقَ عَبْدًا بَيْنَهُ وَبَيْنَ آخَرَ قُوِّمَ عَلَيْهِ فِي مَالِهِ قِيمَةَ عَدْلٍ لاَ وَكْسَ وَلاَ شَطَطَ ثُمَّ عَتَقَ عَلَيْهِ فِي مَالِهِ إِنْ كَانَ مُوسِرًا ‏"‏ ‏.‏