Psalm 57

On the run..........

The song title speaks of the time when David was hiding from Saul in a cave.  Reference I Samuel 22:1;, 24:1-3.

Mercy!   David has fled for his life from Saul.  First he went to Nob, where the priest provided him with food and weapons, and Deog the Edomite, a servant of Saul spotted him and reported back to Saul.  He then fled to Gath, where he was in danger because of his reputation as a warrior, so he pretended maddness to escape them. Also, the Ziphites have betrayed him. Now he's hiding in a cave in the wilderness, pleading for mercy from God.

But note he doesn't just plead for mercy and leave it at that. He praises God, reiterating His attributes.  God is his protector, refuge, defender, and provider.  He does all things for David.  
Like a baby bird is totally dependent on its mother for protection, so is David dependent on God. He depends on God to be true and merciful, to save him,.....to "reproach the one who would swallow" him up.  It seems he is speaking specifically of Saul here.

Verses 4-6 speak of the magnitude of the evil around him.  All around are those who slander and scheme, but David knows his God is greater still, and will be exalted above them all.   Indeed his enemies will fall by the very schemes they have devised against him.

Unwavering, David will praise his God, even in the trying times.  This is his norm.

He will 'waken the dawn' with singing and praise.......I see 2 possible applications for this.  First, worship is the first order of the day.  He is saying that he will waken with praise to God on his lips.   Or......on sleepless nights of turmoil, when sleep won't come, and the dawn comes before sleep....he will be found praising God instead of fretting.

And his praise of the Almighty God won't be quiet.....but he will declare God's greatness to all!