David knew well that
The sacrifice of the wicked is an abomination:
How much more, when he bringeth it with a wicked mind!
'Cease to do evil' comes before 'learn to do well' (Is. 1:10-17). Many were saying, 'Who will show us any good? and David's answer is, 'LORD, lift up the light of Thy countenance upon us'. This is in keeping with the blessing of Aaron and his sons upon the children of Israel:
The LORD bless thee, and keep thee:
The LORD make His face to shine upon thee, and be gracious unto thee:
The LORD lift up His countenance upon thee, and give thee peace.
The sons of Korah sang in Psalm 42: 5,11; 43:5:
Hope thou in God: for I shall yet praise Him
For the health of His countenance.
Then David speaks of a gladness that the Lord can put in the heart more than the natural joy of harvest in those who have their corn and wine increased.
The psalm ends in a note of sweet confidence:
In peace will I both lay me, down and sleep:
For Thou, LORD, alone makest me dwell in safety.
The psalmist had a perfect confidence in the Lord who was everything to him.