In the Book of Mormon we read that the Amlicites marked themselves and the Lamanites were cursed for their rebellion. Alma 3:4-10 "And the Amlicites were distinguished from the Nephites, for they had marked themselves with red in their foreheads after the manner of the Lamanites; nevertheless they had not shorn their heads like unto the Lamanites. Now the heads of the Lamanites were shorn; and they were naked, save it were skin which was girded about their loins, and also their armor, which was girded about them, and their bows, and their arrows, and their stones, and their slings, and so forth. And the skins of the Lamanites were dark, according to the mark which was set upon their fathers, which was a curse upon them because of their transgression and their rebellion against their brethren, who consisted of Nephi, Jacob, and Joseph, and Sam, who were just and holy men. And their brethren sought to destroy them, therefore they were cursed; and the Lord God set a mark upon them, yea, upon Laman and Lemuel, and also the sons of Ishmael, and Ishmaelitish women. And this was done that their seed might be distinguished from the seed of their brethren, that thereby the Lord God might preserve his people, that they might not mix and believe in incorrect traditions which would prove their destruction. And it came to pass that whosoever did mingle his seed with that of the Lamanites did bring the same curse upon his seed. Therefore, whosoever suffered himself to be led away by the Lamanites was called under that head, and there was a mark set upon him."
In the Old Testament we read that if we are righteous servants of the Lord, no weapon formed against us will prosper and the Lord will condemn every tongue that rises up in judgment against us. Isaiah 54:17 "No weapon that is formed against thee shall prosper; and every tongue that shall rise against thee in judgment thou shalt condemn. This is the heritage of the servants of the Lord, and their righteousness is of me, saith the Lord."
In a verse with a thought booklet we're told that when we come to the Lord in prayer, first we need to forgive anyone we have a grudge against. If we expect the Lord to forgive us, we need to forgive others. That's usually easier said than done. The story is told of someone who lost their dog and was distraught. They visited an animal shelter who said they had a dog of similar breed there, but it was not the right dog. They were posting signs about their lost dog when they saw a sign for a lost dog that was of the same breed as their dog. They called that dog owner and mentioned that they'd seen a similar dog at the shelter. Later that dog owner called to thank them. The dog at the shelter had been his! And he then mentioned that he'd just noticed a dog like his in the alley behind his house. Sure enough it was their dog! When they got outside themselves to be concerned about somebody else's dog, it had resulted in them finding their own dog. This same principle may help us forgive others when we find it impossible. If we stop thinking about ourselves and think of others it just might take our focus off what we're angry or upset about and allow us to forgive. We don't necessarily have to do something kind for the person we're upset with (although that would be ideal!) but even if we can do a kind deed for a neighbor, or go out of our way for a family member, that will help us start thinking of others and not of our own hurts. It's worth a try. Mark 11: 25 "And when ye stand praying, forgive, if ye have ought against any: that your Father also which is in heaven may forgive you your trespasses."