What is the ruling on selling fruit now at the price of fruit several months from now?

If a sale contract is concluded for a fruit at a known price, and the payment is deferred, the sale is valid as long as the price is something for which a sale can be deferred. It does not matter whether the price is equal to the current market price, or more, or less, because there is no legal impediment. However, if the price is not specified, such as if the seller says: "I will sell you the kilo at its price after three months," then the sale is invalid due to the ambiguity of the price. This is a gharar (uncertainty) sale and an unlawful consumption of wealth because mutual consent has not been achieved. If the intention is to sell the fruit before it ripens, this is not permissible due to gharar.