What does it mean to let your yes be yes and your no be no?

It is quite enough that in our converse with brethren or other men, our yea should be yea, and our nay nay. "That which is more cometh of evil." The believer is as responsible to speak as to act as in the presence of God. This is his habitual privilege, and safeguard. It may be forgotten by others, or by himself to his loss. The evil one is a liar and the father of it. No small opportunity would it be to him if the Christian were not always watchful to speak truly, and needed such expletives to gain credit for it.

"But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these, cometh of evil." If our words are honest and true, they need no other confirmation than "yes" or "no." The sense of this double mention of yes and no becomes clear from a very similar passage in James 5:12: "Yes" should really mean "Yes," and "No" should really mean "No." All that is more than that is only a sign that one generally does not take the truth too seriously, and therefore "cometh of evil."

If the oath only serves as confirmation of ones own words, because one fears that they are not believed, it is not allowed. As children of God, we should always speak the truth (Eph. 4:25). This should not need any additional confirmation.

(V. 12). The Apostle has warned us against impatience in the presence of wrongs that would seek to revenge the wrongs in forgetfulness that “the Judge stands before the door.” By thus taking our case into our own hands we may fall into condemnation (verse 9). Now he warns us that there is another way in which we may forget God and come under condemnation. In complaining against men, we may forget the presence of God; but also in defending ourselves we may so forget what is due to God that we seek to confirm our statements by irreverently invoking the Name of God, or heaven, or earth. It is the utmost irreverence, in the heat of passion, to use divine Names to seek to gain credit before men. The Apostle therefore says, “Above all things, my brethren, … let your yea be yea; and your nay, nay.”

Then another snare is connected with this for avoidance: "Above all things, my brethren, swear not, neither by heaven, neither by the earth, neither by any other oath: but let your yea be yea; and your nay, nay; lest ye fall into condemnation." What has the apostle in view here? The oath before a magistrate? In no wise does scripture slight that solemn obligation. The Lord Himself respected the adjuration of the high-priest; and in no passage whatever do we see a depreciatory allusion to a judicial oath in the sermon on the mount, or, in what James says here, or in any other part of the Bible, but the contrary. The Lord was addressing Jewish disciples, James writes to the twelve tribes of Israel who are in the dispersion; but what they both set their faces against was the habit of bringing in religious asseverations for the purpose of confirming their word every day, besides the profaning of the Lord's name in matters of this life. This in point of fact weakens instead of establishing what is said; for it is evident that whatever is uncalled for gives no strength to an assertion, but is just a fruit and proof of weakness. Where there is simple truth, nothing is needed but the quiet statement of the fact.

Therefore James says, "Above all things." He would have us, in calmness and quietness, affirm what we have to say with a yes or a no, in the fear of God. It is of all importance, that we should hold in check the movements of nature. We should do it if we saw God before us; we should certainly do it in the presence of a man whom we wished to please. Now God is always present; therefore, to fail in this calmness and moderation is a proof that we have forgotten the presence of God.

Oaths displayed still more the forgetfulness of God, and the actings consequently of the self-will of nature. "Yea," ought to be yea, and "Nay," nay. The actings of the divine nature in the consciousness of the presence of God, and the repression of all human will and of sinful nature, is what the writer of this epistle desires.

The disciples of the Lord Jesus must learn that it is not the torrent of words and excessive affirmations and repetitions which give weight to their words, but that God delights in "truth in the inward parts" (Psa. 51:6), as well as outwardly. Paul writes to the Ephesians, "Wherefore putting away lying (i.e. everything that is false and untrue), speak every man truth with his neighbour" (Eph. 4:25).

There was no guile on the lips of Jesus, nothing ambiguous, nothing but what proceeded from a pure heart, words that conveyed the true feelings of His heart to those who heard Him; and this is what we are called upon to imitate. The natural man so often seeks to take advantage of others by saying something that is calculated to give an entirely wrong impression. This was never found in Jesus, nor should it be found in any who profess to follow Jesus.

In the third and fourth cases (31-37) He again shows us that what was ordained through Moses did not express the full mind of God. Both divorce and swearing were permitted, and thus the standard that men had to attain was not made too severe. Both matters are here set in a fuller light, and we see that only one thing is to be permitted to dissolve the marriage bond; and then that men's word should be so unequivocal and binding, that taking strong oaths, by this or that, is not needed. The man, who backs nearly every assertion by an oath, is a man whose simple word is not to be trusted.