Humayd (may Allah have mercy on him) said that Qadi Shurayh (may Allah have mercy on him) would not grant release from liability for a disease-defect until it had been shown.
Yahya (may Allah have mercy on him) said: (He would say:) I declare release from such-and-such; and even if a disease set in during that interval, they would not be released from it until this defect had been shown to him.
(b) Ibrahim al-Nakha'i (may Allah have mercy on him) said concerning a man who sells his goods and declares himself free of liability for disease-defects: He is free of whatever he named.
(c) Qadi Shurayh (may Allah have mercy on him) said: He is not released until he places his hand on the place of the disease. Ata bin Abi Rabah (may Allah have mercy on him) said the same.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10788