What is the ruling on this sale, and is it permissible to deduct from the monthly salary to pay the remaining amount?

It is permissible to deduct from the buyer's salary to pay for land installments if the percentages are known, even if they vary monthly, provided that the payment mechanism and the completion date are specified, and that the installments do not exceed the agreed price. However, if the salary is not regular and the installments cannot be determined, then the sale is not permissible due to the uncertainty of the term, as "it is not permissible to sell for a price with an unknown term."