to the seller: “Did you sell it to so-and-so for nine?” He replies, “Yes.” He then says, “I will give you ten for it.” This is called purchasing over another’s purchase, and it is not lawful, based on the textual and rational evidence mentioned earlier.

The apparent meaning of the author’s words is that selling over one’s brother’s sale is permissible after the option period has expired, as indicated by his saying, “so that he may rescind [the sale].” For he can only rescind during the option period; after it has expired, he has no right to rescind. Accordingly, it is permissible at that point to sell over one’s brother’s sale. This is the established position of the school.

An example during the option of the session: if we were sitting together and Zayd sold an item to ‘Amr for nine, then, after the seller had concluded the sale with him, one of those present said, “I will give you ten,” this would be purchasing over another’s purchase during the option period and would therefore be prohibited. In this case, the seller is able to rescind the sale.

Likewise, if it were during an option stipulated by condition—for example, if he sold him an item for ten and reserved for himself the option for two days—then someone came on the second day and said, “I will give you eleven for it,” this would not be lawful, because in that situation he is able to rescind the sale and enter into a contract with the second person. But if there is no option, the scholars differ concerning this issue: is such selling and purchasing permissible or not?

I will give an example by which the ruling may become clear. Zayd sells an item to ‘Amr for ten; he receives the payment, the latter receives the item, and they part company, with everything concluded. Then someone comes to the buyer and says, “I will give you the like of it for nine, or something better than it for ten.” This is called selling over another’s sale. Is it permissible or not?