And grieve not the holy Spirit of God, whereby ye are sealed up unto the day of redemption.
Let all bitterness, and wrath, and anger, and clamour, and evil speaking, be put away from you, with all malice;
And be ye kind to one another, tenderhearted, forgiving one another, even as God for Christ's sake hath forgiven you.
I really needed to read this the other day. I think I'm going to memorize it so I can recite it to myself. Now, I don't think I would describe myself as malicious, but I also don't think it's a huge secret that I can be pretty moody. I'm sure my mom and siblings could attest to that; looking back I can tell I was that way even when I was little. And the worst part about me during a bad mood is that I'm usually convinced that I'm right about whatever I happen to be dwelling on during said mood.
I was in such a mood when I read this, and it certainly was humbling. More often than not, I just need to forget about whatever it is that I am brooding over and follow the commandment (yes, commandment) to be cheerful and kind and to direct only positive feelings toward others. I remember being a teenager and having an argument with my sister. Because she knew it would get my goat, she threw out, "You're only hurting yourself if you get mad; you can't control what people do, you can only control how you react." This was the worst possible argument because it totally disregarded my legitimate reason for being mad at her, and it was totally true. But really, most things that we get irritated or even angry over don't matter enough for us to dwell on. It doesn't matter who was right or wrong or what should have been done; it matters that we love God and love others and maintain good relationships with them. This is especially true with our families, with whom we spend the most time and therefore have the most run-ins, but who are the very most important to our spiritual welfare and eternal progression.
I also think this scripture is particularly potent because it reminds us that God forgives us "for Christ's sake" - Christ, who forgot Himself completely, gave His whole life, then suffered and died so that we could be forgiven. It is because of His love for us and for all of the people with whom we associate that we can be forgiven.
Can ye be angry, and not sin? let not the sun go down upon your wrath. Ephesians 4:26, JST
See that ye love one another; ... learn to impart one to another as the gospel requires... And above all things, clothe yourselves with the bond of charity, as with a mantle, which is the bond of perfectness and peace. Doctrine and Covenants 88:123, 125
Perfectness and peace sounds a lot nicer than a bad mood.