Psalms 3: 1 O Lord, how many are my foes! Many are rising against me; 2 many are saying of my soul, there is no salvation for him in God. Selah
Even in modern times we feel this way. The "foes" may not be neighboring armies or political rivals like they were for David, but we all have felt that feeling that they are "all out to get us." Sometimes, depending on our social circle or work enviroment, it may even be true. What advice does the Lord have for us?
3 But you, O Lord, are a shield about me, my glory, and the lifter of my head. 4 I cried aloud to the Lord, and he answered me from his holy hill. Selah
The advice is to take refuge in the Lord, to cry to him, and to pray to him. The Lord answered the prayers of King David, and so to will answer yours if you cry out when the enemies (whoever or whatever those are for you) are at the gate.
5 I lay down and slept; I woke again, for the Lord sustained me. 6 I will not be afraid of many thousands of people who have set themselves against me all around.
Peace to sleep was given to David, and when he woke up, the Lord removed his fear of the trial that lay before him. When I think about what that means to me in those dark times in my life, not to worry about those who are set against me, it gives me a new spring in my step and peace in my heart.
7 Arise, O Lord! Save me, O my God! For you strike all my enemies on the cheek; you break the teeth of the wicked.
Without the fear, he still continues to pray for the resolution to situation. He prays for justice, that those who do wicked would have their teeth broken; don't think that God will answer a prayer that isn't just.
8 Salvation belongs to the Lord; your blessing be on your people! Selah
David acknowledges that God is the one with power of redemption, and he then prays for a blessing from God to be upon the people who have been called.