The Sermon on the Mount tells hearers not to swear at all but to let their yes be yes. Quakers and Anabaptists read this flatly, and English Quakers refused judicial oaths from the 1650s onward at real cost — imprisonment, inability to give evidence, and exclusion from public office. The affirmation now available in most common-law courts exists because they kept refusing until the law changed, and the same principle underlies conscientious objection provisions. The mainstream of the tradition read the passage as forbidding casual and manipulative oath-taking rather than the solemn kind, which is convenient but not obviously wrong, since Paul himself calls God to witness in his letters. The deeper claim is about the ordinary word: an oath implies a lower standard applies when you are not under one.