Restore unto me the joy of my salvation
the word SALVATION means= Preservation or deliverance from destruction, difficulty, or evil.
b. A source, means, or cause of such preservation or deliverance.
This joy, ......gladness, is not happiness that depends on our circumstances and our moods;
which has to do with our emotions or station in life.
This joy is something that is constant; ......it is from within us because He lives within.
One can have the same joy in terrible circumstance, that they would have when all is well, the same attitude of being on the mountain top when they are in the valley.
And....it was obvious that due to what David had done......(this is when he had Uriah killed and got Bathsheba pregnant) that he had lost the Joy of the Lord.
He might even have thought he’d lost his salvation as he asks “Restore unto me the joy of my salvation, and renew a right spirit within me".
Jesus makes two particular statements about joy for us....
in John 15:11: "These things I have spoken to you, that My joy may remain in you, and that your joy may be full.”
John 17:13-14: "But now I come to You, and these things I speak in the world, that they may have My joy fulfilled in themselves. "I have given them Your word; and the world has hated them because they are not of the world, just as I am not of the world.”
For now, this joy involves faith....
1 Pet. 1:8-9: “whom having not seen you love. Though now you do not see Him, yet believing, you rejoice with joy inexpressible and full of glory, receiving the end of your faith-- the salvation of your souls.”