Okla. Stat. tit. 60, § 175.47
The absolute power of alienation of real and personal property, or either of them, shall not be suspended by any limitations or conditions whatever for a longer period than during the continuance of a life or lives of the beneficiaries in being at the creation of the estate and twenty-one (21) years thereafter, except when property is given, granted, bequeathed, or devised to a charitable use or to literary, educational, scientific, religious, or charitable corporations for their sole use and benefit, or to any cemetery corporation, society or association, nor shall this section apply to gifts, grants, devises, or bequests absolute, limited, or in trust, for the advancement of medical science to an incorporated state society of physicians and surgeons.
Laws 1941, HB 174, p. 264, § 47.