Mishnayos Bava Metzia Perek 5 Mishnah 3

הבא מעות וטול את שלך אסור – He who brings excess monies that are upon you [to bring] and take your field, it is forbidden to do this. As in such a case where the seller said to the purchase: Go bring me excess monies and you purchase it from now, therefore, it is forbidden to do this, for if the seller were to consume the produce during this period, when he (i.e., the purchaser) brings the money, it is found that this field was sold to him from the day of the sale, but this one (i.e., the seller) ate the produce as the reward while waiting for the monies. But if the purchaser would consume the produce from now, for perhaps he would not bring the excess monies and would return to him (i.e., the seller) what he had received and it would be that the field had not been sold to hm, for when he would bring it (i.e., the monies), it would be sold to him from now he told him, but he didn’t bring it, and the first monies are like a mere loan in regard to the seller, and he ate the produce with his payment.

הרי היא שלו – in such a case as when he (i.e., the purchaser) said to him, buy it from now – if I don’t bring to you [the monies] from now until three years, it is not an Asmakhta (i.e., a collateral security with the condition of forfeiture beyond the amount to be secured – see Bava Batra 168a), but a complete purchase, for on the condition that he sold it completely, he would hold it from now with these monies and he would lower the price and sell (some of the movable goods in order to raise the money – see Bava Metzia 77a), and he who received it, if he would return him his monies within three years, would receive them, and the produce would be left in the hand of a third-party, and if the borrower returned his monies to the lender within the three years, he would release the produce to the borrower, and if not, he would give the produce to the lender, for the field was sold to him at the time of the loan, and that loan was the cost of the field.