One of the transactors stipulates the sale

A sale is not binding by offer (or acceptance) alone. In fact it will only be binding if both, the offer and acceptance are effected. If one of the contracting parties places an offer of sale, then the other has a choice, if he pleases he may accept or reject during that same sitting. If he accepts then the sale will be binding. In the case of acceptance, neither of the parties will have a choice (of rescinding the sale) (Kitaabul Buyoo).