Sayyiduna Abu Hurayrah (may Allah be pleased with him) says that a man freed his share in a slave, so the Prophet (peace and blessings be upon him) upheld his freeing and charged him with paying the value. Qatadah (may Allah have mercy on him) says: If he has no wealth, let the slave be made to work, but without being overburdened.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العتق / 21375