Qitzur Shulchan Arukh – 66:11
Similarly, if Re’uvein owes Shim’on money, but when the payment date arrives Re’uvein has no money so they makes an agreement that Shim’on wait for him some time, this also is not fixed [i.e. made permissible] by a business agreement. Rather, Re’uvein should sell to Shim’on some merchandise that he has using the method described above, Shim’on should return to him the IOU which he already had, and Re’uvein gives him a note for the merchandise which he bought from him, using the method described above. [Thereby terminating the old, defaulted, loan, and starting a business agreement.