"Where time was of the essence of a broker's contract for the sale of land, an extension of time should be pleaded in order to justify evidence thereof and its submission to the jury.

Leuschner v. Patrick (Tex. Civ. App. '07), 103 S. W. 664; Whitelock v. Beach, 160 S. W. 815, 174 Mo. App. 428.