وإن وجدها أكثر من الذراع الذي سماه فهو للمشتري ولا خيار للبائع
Translation: If it is found larger than the specified cubit-measure, the extra belongs to the buyer and the seller has no option.
An identified cloth is described as 10 cubits but proves to be 12. In this lump-sum sale, the entire identified cloth belongs to the buyer; additional length improves the described attribute of that same item.
The seller does not acquire an option to demand a new price for the two extra cubits or cancel on that account.