the dyeing, and every other expense meant to enhance the item’s resale value. If he himself performs the fulling, the weighing, or the transport, or if someone volunteers to do it, no wage is added for that labor. Both parties must be aware of the exact price—or of the total outlay incurred; should either of them be ignorant of it, the contract is void according to the sounder view.

The seller is to be believed about the amount of the original price, the payment term, the fact that he acquired it through barter, and any defect that arose while the item was in his possession. Thus, if he says, “It cost one hundred,” and it later proves to have cost ninety, the preferred opinion is that the excess and its corresponding profit are simply deducted, and the buyer has no right of rescission. But if he claims it cost one hundred and ten and the buyer accepts that figure, the more reliable position is that the sale is invalid. I say: the soundest opinion is that the sale remains valid, and Allah knows best.

If the buyer accuses him of lying and he can offer no plausible explanation for the mistake, neither his statement nor any evidence he produces is accepted; nonetheless, he may—according to the stronger view—require the buyer to swear that he has no knowledge of the matter. If he does put forward a plausible explanation, he still has the right to demand the oath, and the preponderant view is that his evidence is then admissible.