As with many of the words in the intros to the Psalms, scholars really don't know for sure what a Shig-gaw-YONE is. It is only used here and by the prophet Habakkuk.
Hab. 3:1 A prayer of Habakkuk the prophet, according to Shigionoth.
It is possible that it is from the Arabic word "Shaga," which means "to be anxious or sorrowful." Thus, it would denote a sad song of affliction.
David is singing this song about Koosh, a Benjamite. Again, there is a bit of mystery surrounding his identity. It is possible that this is simply a man named Koosh that is nowhere else mentioned in Scripture. It is possible that it refers to King Saul, under a variation of his father's name, Kish. The third possibility that seems plausible is that because the word "koosh" means "black," and is used as a put-down when referring to someone with a "black mind" or a "black heart" or having "black morals," it may be any other of David's enemies that he is referring to using an epithet rather than naming them.
From the beginning of the psalm, we see that David has taken refuge in the Lord from the onslaught of his enemies. Psalm 18 says,
Ps. 18:30 He is a shield to all who take refuge in Him.
This is a promise that if you will take refuge in the Lord, He will be a shield to you.
But the question remains, how do you practically take refuge in the Lord? It goes back to my favorite Bible promise:
Phil. 4:6 Be anxious for nothing, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God, which surpasses all comprehension, shall guard your hearts and your minds in Christ Jesus.
The Lord shields our hearts and minds when we pray, petition, and give thanks.
David is saying to the Lord, "Hey, if I've done what I'm being accused of, let him go ahead and kill me - a man reaps what he sows." A lot of people don't pray like this very much - openly, honestly, wanting to know the truth even if it is against them. But David wanted to know whether he was in the wrong here.
Jesus said,
Matt. 7:2 "For in the way you judge, you will be judged; and by your standard of measure, it will be measured to you.
Matt. 7:12 "Therefore, however you want people to treat you, so treat them, for this is the Law and the Prophets.
It amazes me how many Christians live their lives as gossips, and then are outraged when someone gossips about them. And how many are judgmental, and then are outraged when someone judges them.
Remember, David had no presumption that he was sinless. For example, in Psalm 6 we saw him appealing to God's mercy for his sin.
Being without reproach in the matter, David asks God for vindication. Again, we see a man with a heart after God, who submits problems to the Lord rather than taking them into his own hands.
Rom. 12:19 Never take your own revenge, beloved, but leave room for the wrath {of God,} for it is written, "VENGEANCE IS MINE, I WILL REPAY," says the Lord.
Let's leave revenge up to God.
Here we see the picture of an angry God who hates sin and judges it. But there is also the way of escape: repentance. Turning away from our sin and doing right. Peter wrote,
2Pet. 3:7-9 ...The present heavens and earth by His word are being reserved for fire, kept for the day of judgment and destruction of ungodly men. But do not let this one {fact} escape your notice, beloved, that with the Lord one day is as a thousand years, and a thousand years as one day. The Lord is not slow about His promise, as some count slowness, but is patient toward you, not wishing for any to perish but for all to come to repentance.
God will justly bring judgment soon, but mercifully is waiting for people to repent.
David reassures us that the wicked will be judged. Some on earth, others after they day. Paul wrote to the Galatians,
Gal. 6:7 Do not be deceived, God is not mocked; for whatever a man sows, this he will also reap.
A man who digs a pit will fall into it. A man who sets a trap will be caught. A man who steals will lose what he has stolen. The proverb says,
Prov. 26:27 He who digs a pit will fall into it, and he who rolls a stone, it will come back on him.
And even if a man manages to escape these curses, He will one day stand before God and be sent away.
Often, I find myself only giving thanks when something wonderful happens. But this world is wicked, and if I only give thanks and praise then, I will not be thankful or praising much of the time. My thanksgiving is not to be based on man's unrighteousness, but on God's righteousness. Then I will thank and praise continually.