Is it permissible to purchase agricultural land with a preliminary contract and pay half its price, then sell part of it to pay the remainder of the price, before registration with the final contract?

If the preliminary contract is a valid sales contract, the buyer may sell the land or part of it before paying the full price, as long as the legitimate conditions of sale are met. However, if the preliminary contract is merely a promise to sell, then it is not permissible to sell it until ownership has been transferred. And if the preliminary contract is a sales contract that prevents the buyer from disposing of the property until the full price is paid, then it is not permissible to sell the land except with the seller's permission.