No person shall be excused from testifying in any civil action, to any facts showing that an evidence of debt or thing in action has been bought, sold or received contrary to law, upon the ground that his testimony might tend to convict him of a crime. But no evidence derived from the examination of such person shall be received against him upon any criminal prosecution.
Okla. Stat. tit. 21, § 564
Privilege of witnesses in respect to claims or debts sold
R.L.1910, § 2276.
Official source: Oklahoma Legislature. Reproduced from public-domain Oklahoma statutes; confirm against the official source for the current text. Not legal advice.