The plaintiff's disavowal of the contract relieved the defendant of the necessity of tendering the purchase price within the period of the option. Such a tender would have availed nothing according to the testimony of record. The law does not require the doing of a vain thing. The disavowal was a waiver of the requirement. Phelps v. Davenport, 151 N.C. 22, 65 S.E. 459; Gaylord v. McCoy, 161 N.C. 685, 77 S.E. 959.

In this view of the matter, the evidence was quite sufficient to carry the case to the jury on the defendant’s counterclaim. Crotts v. Thomas, 226 N.C. 385, 38 S.E. 2d 158; Trust Co. v. Frazelle, 226 N.C. 724, 40 S.E. 2d 367; Cunningham v. Long, 186 N.C. 526, 120 S.E. 81. Hence, the dismissal of the counterclaim will be reversed, and the directed verdict and judgment for plaintiff set aside and a general new trial ordered.

Reversed and new trial.