I will not be afraid of ten thousands of people, that have set themselves against me round about.
 Arise, O LORD; save me, O my God: for thou hast smitten all mine enemies upon the cheek bone; thou hast broken the teeth of the ungodly.
 Salvation belongeth unto the LORD: thy blessing is upon thy people. Selah.
3:5,6 I laid me down and slept: Although David was continually under stress, by God's grace he still was able to experience a night of rest. This was possible only because of God's sustaining power in his life. I will not be afraid: God is his protector and David has no need to fear (23:4; 27:3; 118:6).
3:7,8 David calls out for God to arise, He is trusting God to intervene on his behalf. Smitten all mine enemies upon the cheek bone: David's enemies are likened unto powerful beasts whose strength is in their jaws and whose terror is in their teeth. However, they are no longer a threat because God has saved him from these wicked ones. Salvation, refers to God's deliverance from these and that is the reason he can rest.