What is the ruling on purchasing an item from a store and paying for it later, or paying part of its price and deferring the remainder?

It is permissible to sell for a price that is either immediate or deferred, as long as it is known. If the sale is concluded without any specific mention of the payment terms, the price is considered immediate, and the seller has the right to demand it from the buyer at any time, because immediate payment is an implicit requirement of the contract. So, if the buyer says, "I will give you the price later," and they conclude the sale without stipulating a deferred payment, the sale is valid, and the seller has the right to collect the full price. However, if the sale is concluded with the condition of deferring the price for an unknown period, there has been a difference of opinion among scholars regarding its validity.