I believe if you check the Commentaries Bro. Gary, you will have a more clear picture of this verse.
Matthew Henry's Concise Commentary
5:33-37 There is no reason to consider that solemn oaths in a court of justice, or on other proper occasions, are wrong, provided they are taken with due reverence. But all oaths taken without necessity, or in common conversation, must be sinful, as well as all those expressions which are appeals to God, though persons think thereby to evade the guilt of swearing. The worse men are, the less they are bound by oaths; the better they are, the less there is need for them. Our Lord does not enjoin the precise terms wherein we are to affirm or deny, but such a constant regard to truth as would render oaths unnecessary.
Gill's Exposition of the Entire Bible
But let your communication be yea, yea,.... That is, let your speech, in your common conversation, and daily business of life, when ye answer to anything in the affirmative, be "yea"; and when ye answer to anything in the negative, "nay": and for the stronger asseveration of the matter, when it is necessary, double these words; but let no oaths be joined unto them: this is enough; a righteous man's yea, is yea, and his no, is no; his word is sufficient. Hence it appears, that our Lord is here speaking of rash swearing, and such as was used in common conversation, and is justly condemned by him. The Jews have no reason to reject this advice of Christ, who often use and recommend the same modes of expression. They endeavour to raise the esteem of their doctors and wise men, by saying, that their words, both in doctrines and dealings with men, are "yea, yea"
. One of their (z) commentators on the word "saying", in,
Exodus 20:1 makes this observation;
These two examples show that the Verse is referring to "EVERY DAY" conversations between men. Not Legal Contacts or some such that is required by Law. We are taught to obey the Law of man for the glory of God.
God bless, hope you have a blessed New Year!