What is the ruling on selling by installments without specifying the installments or payment dates within a known period, or by specifying them and offering promises of leniency for delays or a reduction in the amount?

As for the first case: If the intention is that the price must be paid in installments over the months of the year without specifying the installment amount for each month, then this is not permissible due to the ambiguity (Jahalah) in the due dates of the installments.

As for the second case: If the agreement obliges the buyer to pay on the agreed-upon dates, then this is a valid agreement, and there is no harm in granting him a respite if he faces difficulty in payment.