Psalm 4:3, 8
But know that the Lord has set apart for Himself him who is godly;
The Lord will hear when I call to Him.
I will both lie down in peace, and sleep;
For You alone, O Lord, make me dwell in safety.
God has set apart His faithful servants for Himself and deals wonderfully with them.
God hears and responds when we call to Him.
We can lie down and sleep in peace and with a tranquil heart because God alone makes us dwell in safety and confident trust.