He will be debiting accounts payable and crediting notes payable. According to the concept of accounting, a liability will be gained if it is recorded as a credit and will be lessened if the liability is debited. In this situation, the accounts payable will be lessened and will be replaced by a notes payable instead. So in order to lessen the accounts payable, you have to debit it. Of course you will also be gaining a notes payable. You can do this be crediting the notes payable.
