Okla. Stat. tit. 58, § 61
When a will has been admitted to probate, any person interested therein may at any time within three (3) months from the date the will was admitted to probate contest the same or the validity of the will. For that purpose he must file in the court in which the will was proved a sworn petition in writing containing his allegations, that evidence discovered since the probate of the will, the material facts of which must be set forth, shows:
R.L. 1910, § 6219; Amended by Laws 1953, HB 676, p. 233, § 6; Amended by Laws 1967, SB 37, c. 10, § 1, emerg. eff. February 20, 1967.