Imam al-Sha'bi (may Allah have mercy on him) said: A man bought a slave from someone and also took earnings from him; then he found in him a disease that had already existed while he was with the seller. They took the dispute to Qadi Shurayh, and he said: He is to be returned because of the disease, and the earnings are yours in return for the liability.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10744