Okla. Stat. tit. 21, § 21-562: Receiving claims in payment of debts

Nothing in the preceding sections shall be construed to prohibit

the receiving in payment of any evidence of debt or thing in action

for any estate, real or personal, or for any services of any

attorney actually rendered, or for a debt antecedently contracted,

or the buying or receiving any evidence of debt or the thing in

action for the purpose of remittance, and without any intent to

violate the preceding section.