Okla. Stat. tit. 12, § 12-431
Use of affidavit
An affidavit may be used to verify a pleading, to prove the
service of a summons, notice or other process in an action, to
obtain a provisional remedy, an examination of a witness, a stay of
proceedings, or upon a motion or in any other case permitted by law.
R.L. 1910, § 5071.