Where M., who was to receive a commission for a sale of B.'s land, turned over the sale of the land to L., agreeing that L. should have the commissions therefor, to which B. consented before a sale was made, L., on selling the land, was not entitled to a commission as the assignee of M., but because he, with the knowledge and consent of B., sold the land after M. had waived his right to do so. Munson v. Mabon, 135 Iowa, 335, 112 N. W. 775.