And my soul shall be joyful in the Lord; It shall rejoice in His salvation. (Ps 35:9)
David takes here a decision. He decides to be joyful in the Lord... a joyful heart cannot bear anxiety. Although a situation may be pitch-black, we can rejoice in His salvation. If God did not spare his own son, but gave Him up for us, how much more will He not also save us from every sin. Let us yield ourselves to Him, that He might accomplish his great cause in us!