Gibbs, Jeffrey A. “Matthew 5:33-37: On Oaths." St. Louis: Concordia Publishing House, 2006, pp. 297-300.
In Matthew 5:33-37 Jesus speaks of making and breaking oaths. Gibbs observes that the idiom used here differs from that of Exodus 20:7 and Deuteronomy 5:11. His conclusion is that Jesus is not actually citing the Old Testament though he is referring to an Old Testament principle (Gibbs 2006, 297). Promises are not to be based on heaven or earth, or on Jerusalem, as they are the special property of God. Jesus refers to such a promise as coming from the evil one (Gibbs 2006, 298).
Gibbs finds in some Palestinian teachers a heirarchy of ways one could swear an oath (Gibbs 2006, 298). Counter to this idea, Jesus is teaching that all promises are binding. Gibbs observes that Jesus' implication is that all things belong to God. Making an oath based on something is a promise before God (Gibbs 2006, 299). Rather, our word is to be our word. Gibbs does not regard this as an injunction against making solemn promises. However, our words are never to be used lightly (Gibbs 2006, 300).