It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever frees his share (of a slave), and he has wealth with which the remaining shares can also be freed, then the value of the slave will be assessed, and that person will pay the other partners their share and free the entire slave on his behalf. If he does not have wealth, then only that portion of the slave will be considered free which he has freed."
Hadith Referenceالسنن المأثورة / باب من أعتق شركا له في عبد / 551
Hadith Takhrijصحیح بخاری، العتق، باب اذا اعتق عبدا بين اثنين الخ، رقم: 2522؛ صحیح مسلم، الأيمان والنذور، باب من اعتق شركاً له في عبد، رقم: 1501۔