A broker must follow the instructions of his employer; therefore, one who is promised compensation if he will procure a purchaser for property on certain terms can not claim compensation for effecting a sale on lower terms, he having, moreover, acted in part in the buyer's interest. Williams v. McGraw, 52 Mich. 480, 18 K W. 227; McDonald v. Cabiness, 100 Tex. 615, 98 S. W. 943, 102 S. W. 720; Yarn v. Pelott, 55 Fla. 357, 45 S. 1015; Ryan v. Page, I11 N. W. 405, 134 Iowa, 60. See also Secs. 141, 422, 898.