The Ten Commandments include the law, “Thou shalt not kill.” Taking this to a deeper level, Jesus gives a new version of this commandment: “Thou shall not be angry with thy brother.” Why taming our tempers and emotions is important in all of our human relations, what Jesus says here is specifically relevant within a religious covenant community. It is unbecoming for members of the covenant community to be angry with each other. We may not call him or her a fool, moros. As with insipid salt, fools are cast out, excommunicated. That kind of demeaning speech used against a member of the community is inappropriate; it is a powerful form of evil-speaking, and there is a strict prohibition against speaking evil of anyone who is among the members of the holy church.
Matthew 5:22 reads, “Whosoever is angry with his brother without a cause,” but 3 Nephi 12:22 does not have the phrase “without a cause.” The Book of Mormon has the stronger statement here. If you are angry with your brother, period, you are in trouble, and you will be in danger of the council and in danger of the judgment of God. In the Greek, the one small word eik? has been translated as “without a cause,” but it can also mean “rashly” or “unseemly.” Perhaps someone inserted that little word later into Jesus’s warning here, thinking that surely Jesus did not mean that we could not ever be angry. However, in the Book of Mormon, Jesus strongly declared that He did not want anger at all among his covenant makers. Some of the earliest manuscripts of Matthew do not have that little word eik?, so the better manuscripts and translations assume that Jesus originally said what the Book of Mormon has him say.