It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "If a slave is jointly owned by two men and one of them frees his share, then in case the other is wealthy, the value of the slave will be assessed."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 4901
Hadith Gradingحکم دارالسلام:إسناده صحيح، خ: 2003، م 1501 .