Our Sheikh Al-Othmani said in the jurisprudence of sales (1: 530): "Among the practices of some merchants regarding deferred debts is that they waive a portion of the debt on the condition that the debtor pays the remainder before the due date. For example, if Zayd is owed a thousand by Amr, Zayd might say: 'Pay me early and I will waive a hundred from you.' This transaction is known in jurisprudence as: 'Waive and pay early.' If this early payment is conditional on waiving part of the debt, then the four schools of thought agree on its prohibition."