Upon filing the petition, a citation must be issued to the executors of the will, or to the administrators with the will annexed, and to all the legatees and devisees mentioned in the will, and heirs residing in the state, so far as known to the petitioner, or to their guardian, if any of them are minors or adjudicated incompetents, or their personal representatives, if any of them are dead, requiring them to appear before the court on some day therein specified, to show cause why the probate of the will should not be revoked. A copy of such citation shall be mailed to all such persons, nonresidents of the state, whose addresses are known to petitioner, at least ten (10) days before such hearing.
Okla. Stat. tit. 58, § 62