The essential antithetical pairing is breaking oaths/keeping one’s word. The particulars are bound up in the cultural contexts of oaths in the Old World. The first phrase deals with the breaking of oath, as “forswear” means to break an oath. (Gary R. Whiting. The Command to be Perfect.” The Book of Mormon: 3 Nephi 9-30, This is My Gospel. Religious Studies Center, Brigham Young University, Provo, 1993, p. 110). The particular setting of this saying is better seen with a different translation of the setup verse, 33:
“Again , you have heard that it was said to the people long ago, ‘Do not break your oath, but keep the oaths you have made to the Lord.’ (Matthew 5:33, New International Version).
The ancient world was one in which there were few written contracts. Contracts would not rely upon the squiggles produced by the hand, but the words produced by the mouth. An oath created the binding of the contract. Because of the order of the English phrase, we tend to focus on the commandment as rendered in the NIV: “Do not break your oath.” In fact, the real focus was on keeping the oaths made to God (see the discussion of the relationship of this saying to Psalm 50 below).
The problem that was being addressed was the cultural assumption that while one must keep an oath to God, other oaths were subject to revision. Thus each of these examples of oaths had its counterpart in Jewish literature, and each is described as a non-binding oath (Robert Guelich. A Foundation for Understanding the Sermon on the Mount. Word Publishing, Dallas. 1982, p. 215). Thus the antithesis is not really swear/not swear, but in reality the essential difference is “find a way to break your word”/ “keep your word.”
This is the context in which we see the “But let your communication be Yea, yea; Nay, nay; for whatsoever cometh of more than these is evil.” It certainly is not saying that we may only speak the words yes or no. The problem is the embellishment of yes or no with the oath that gives it the appearance of being binding, but which is not. The shift from Law to Gospel is one of the technicalities where one may appear to follow the law, but actually intend to violate an oath. For the gospel, one’s word should stand. Embellishing oaths would not be needed if we are simply true to our word. The modern equivalent would be to suggest that all contracts are binding, and that we should not be looking for ways to “break” our contracts. This would violate our word, and it reflects an internal dishonesty.
As with other sayings, this one is qualified in real practice by changing conditions. To apply this saying properly we must remember that the issue is not the contract but the contractor. The problem is not in the action, but in the person making the action. The assumption of the non-binding oaths is that one would make a contract with the intent to break it. This is inherently a dishonest relationship, and therefore to be avoided.
“Jesus counters the Old Testament prohibition of swearing a false oath by forbidding swearing at all in lieu of a straightforward yes or no statement. Taken legalistically, Jesus simply outlawed the use of oaths. Yet, as in the previous Antitheses, the intent is much more radical than merely dispensing with the use of oaths.
In a society built around the use of oaths to guarantee one’s honesty, setting them aside would be as impossible as prosecuting anger or lust. Rather, this Antithesis, consistent with the previous ones, uses a legal concern drawn from everyday life to express Jesus’ demand for conduct consistent with completely new human relationships, a context of total honesty.” (Robert Guelich. A Foundation for Understanding the Sermon on the Mount. Word Publishing, Dallas. 1982, p. 218-9).
Book of Mormon Context: The admonition to total honesty in one’s relationships is as applicable to the New World as it was to the Old, and as it is to the modern world. The specific examples rely upon rabbinic tradition that would have been readily known in the Old World, but which probably did not develop in just such a way in the New World. Even assuming a parallel development of legalism in oaths, the items upon which the oaths would have been taken would have developed in a separate climate, and would doubtless have differed from the Old World. The deletion of the oath on Jerusalem would be the right idea, but the reasoning for its deletion would probably apply to the other examples as well.
As with other textual alterations, this is an indication of the nature of the translation process, not evidence of the underlying plate text. The essential meaning shines through, but does so through the extra layer of the Matthean text upon which the alterations were effected.
Textual: The possible reference for this set is Psalm 50:14:
Psalms 50:14
14 Offer unto God thanksgiving; and pay thy vows unto the most High:
While the parallel, does not appear significant in the KJV English translation, it is nearly verbatim in the Greek Septuagint (Robert Guelich. A Foundation for Understanding the Sermon on the Mount. Word Publishing, Dallas. 1982, p. 212).
The emphasis is on the payment/fulfillment of oaths or vows to God. This is the technical opening that was exploited in the oath-legalism that prompted this saying. This prohibition against swearing in the Sermon on the Mount is echoed in James:
James 5:12
12 But 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.
There are two changes in this section. The first replicates the pattern of changing “saying” to “written” that is common to the 3 Nephi redaction. The next is the removal of a phrase in the Matthean redaction of verse 35. Matthew has the additional “neither by Jerusalem; for it is the city of the great King.” Clearly the reference was removed, as it would not be relevant to the New World context. The Jerusalem of the New World was hardly considered a sacred or important place (see Alma 21:1-4).