The ruling on deferring part of the price of a commodity by an amount greater than the first part

Question:
May Allah reward you with good. I went to the market to buy a specific commodity, and at that time I did not have the full amount. I found the commodity, and its owner said, "If you want to pay the full price, do so; otherwise, pay what you have, and leave the remainder with an additional amount of so much and so much for a specific period of time." Is that permissible, or is it considered riba (usury or interest)?

Answer:
There is a distinction here. If he intends that if you defer the remainder, it will be with an increase, and if you pay it immediately, it will be without an increase, then this is not valid. This transaction is not valid because it is an unclarified sale; it is neither a spot sale nor a deferred sale. It is obligatory that the sale be clarified, either as a spot sale with a spot price, or as a sale with a deferred price, either in full or in part, at the time of the contract. As for the contract being ambiguous between these two, this is an invalid sale. Yes.