Musannaf Ibn Abi Shaybah 22074 — A man who buys something and finds

Ata said: If a man buys some goods and then finds a defect in them, the buyer will need testimony that this defect existed while they were with the seller. If testimony is found, that settles it; otherwise the seller will be made to swear that he did not know of this defect. Amr bin Dinar said: The oath will be taken as to his knowledge.