Musannaf Ibn Abi Shaybah 22124 — Buyer and seller who differ

Shurayh (may Allah have mercy on him) said: If the seller and the buyer disagree and the item sold is still present as it was, witnesses are requested from both. If one of them produces witnesses, it is given to him on the strength of his witnesses. If neither has witnesses, both are made to take an oath. If both take the oath, the sale is annulled, and if both refuse to take the oath, the sale is likewise annulled. If one takes the oath while the other refuses, it is given to the one who took the oath. If the item sold is not present as it was, or it has perished, the seller is charged with producing witnesses and the oath is imposed on the buyer.