Ephesians 4:26 ASV

Ephesians 4:26
This is the opener for today's lesson. I never knew that this "never go to bed mad" kind of saying was from or in the Bible. I don't want to jump the gun and say that this is the first place it showed up, but I'm sure it helped popularize the saying in our culture.
I am glad to see that this is a Biblical idea. Something that I can now stand upon as a first truth and something that I can trust as right and righteous.
Psalm 79:8-10
I don't get it. How does this relate to today's lesson? Is it illustrating how this guy is angry at the pagan/heathens and asking for forgiveness without giving it? Maybe so... It also seems to do with him being mad.
Luke 17:1-4
So, not only should we not sin, do not EVER cause another to sin or temp him with sin. Moreover, if someone does sin against you, you must forgive him EVERY TIME. But, you must also reprimand him and speak solemnly with him.
Psalm 103:11-12
God loves us immeasurably and has divided US from our sins to a distance immeasurable.