Also, rash vows are bad. Vows were abused by minutia. B. Jesus taught that we should always be truthful. Swearing by our own heads implies that failure to comply with the oath would bring some catastrophe upon him, but this is not within man's control. Yet Jesus himself accepted an oath at his trial.
Oaths are unnecessary.
All oath-taking seems to be forbidden. Mennonites take seriously, and won't give oaths in court. Jesus made an oath, but he was divine. Old Testament usage is superseded by Jesus' command. A. Commitment to honesty makes genuine Christians stand out.