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 jointly owned slave, the value of the slave will be assessed. If he does not have wealth, then only the portion he has freed will remain freed."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 6453