Matt 5:34

5:34 Do not take an oath. Some have understood Jesus’ prohibition of oaths to be universal, but Jesus Himself submitted to oath (26:63), and Paul invoked God as his witness in Rom. 1:9. God Himself takes an oath so that we might be encouraged (Heb. 6:17). Jesus is addressing a narrow and misleading legalism that required a specific oath to make spoken words binding. The implication of such an approach to honesty is that we do not need to be truthful except under oath. Jesus demands an integrity of speech as though everything were under oath. He also prohibited the implicit idolatry of swearing by anything less than God. See “Honest Speech, Oaths, and Vows” at Neh. 5:12.