Is it permissible to buy and sell in installments with an increase in the price of the commodity compared to its cash price? Are there specific conditions for installments, such as the type of commodity, the amount of installments, the percentage of increase, and the duration of the installments?

Installment sales are permissible. They involve selling a known commodity for a known price, to be paid at a known future date. The buyer pays a portion of the price over agreed-upon periods to the seller. There is no limit to the increase the seller may take in exchange for the deferment, provided that this increase is specified and agreed upon at the time of the contract.