Okla. Stat. tit. 15 § 2 : CONTRACTS — NATURE OF CONTRACTS —DEFINITION AND ESSENTIAL ELEMENTS — Essential Elements of Contract

It is essential to the existence of a contract that there should be:

1. Parties capable of contracting.

2. Their consent.

3. A lawful object; and,

4. Sufficient cause or consideration.

Okla. Stat. tit. 15, § 2

R.L. 1910, § 876.