Psalms 18:24
Therefore hath the LORD recompensed me according to my righteousness, according to the cleanness of my hands in his eyesight. Therefore hath the LORD recompensed me according to my righteousness, according to the cleanness of my hands in his eyesight.
The Lord recompensed David in proportion to his righteousness and in proportion to the cleanness of his hands as it stood in God's own eyesight. That recompense was measured not by human estimate but by what God saw in the life and conduct.
The righteousness in view is keeping the ways of the Lord and keeping His statutes. It is remaining upright before Him and turning away from iniquity. Those who are worked by Christ are able to affirm with assurance that they have kept God's statutes and have remained upright before Him.
In service for Christ this means God deals truly with those who serve Him. Reward rests not on the amount of work done alone but on the spirit in which it is done. Humble and trusting service, marked by thankfulness and joy, receives a generous reward.