When any sheriff authorized by law to sell real estate makes such sale and dies or vacates his office before making a conveyance to the purchaser thereof, the court from which the writ issued, upon proof of the sale and of the payment of the purchase money, may order the successor in office of the sheriff making such sale to make a conveyance of such lands to the purchaser, and such conveyance shall relate back to the date of the sale. If the purchaser is the plaintiff in the judgment, proof that he has credited, or the fact that he does credit, on the record the defendant with the amount of the purchase money, less the necessary expenses and costs, is equivalent to proof of payment of the purchase money.