and they say that the left-handed person strikes more forcefully. So, if his work with his left hand is more effective than his work with his right, how can this be considered a defect? We have a principle by which to judge: does his being left-handed diminish his value? If those engaged in the slave trade say that it does not diminish his value, then it is not a defect; but if they say that it does diminish it, then it is a defect. If he is ambidextrous, however, it is not a defect, because this is an added advantage. An ambidextrous person is one who works equally well with both hands. Some people can use their right and left hands alike: they write with the right hand and write with the left hand. Thus, if one finds a person who is ambidextrous, this is an added advantage.
The author has confined himself to examples. In al-Rawḍ (1), many further examples are mentioned, but there is no need to read them, since we have a governing criterion: a defect is anything that diminishes the value of the item sold.
“If the buyer learns of the defect thereafter, he may retain it with compensation for the defect, which is the proportion represented by the difference between its sound value and its defective value; or he may return it and take back the price, …”
His statement, “If the buyer learns of the defect thereafter”: the subject is the buyer. This applies when the defect is in the item sold; or it may be the seller, when the defect is in the price, and this is possible.
For example, I sell you a sheep in exchange for goats: the sheep is the item sold, and the goats are the price. Thus, whether the buyer or the seller discovers a defect in a specified price [the ruling applies].
His statement, “thereafter,” raises a grammatical issue, since the word is in the nominative even though it is an adverb of time.
The answer to this issue is that the governed noun has been omitted while its meaning is intended. It therefore becomes indeclinable with a ḍammah; thus, the vowel here is a vowel of indeclinability, not one of grammatical inflection.