Charles H. Spurgeon on Psalms 19:11

"In keeping of them there is great reward." Not only for keeping but in keeping of them. As every flower hath its sweet smell, so every good action hath its sweet reflection upon the soul: and as Cardan saith, that every precious stone hath some egregious virtue; so here, righteousness is its own reward, though few men think so, and act accordingly. Howbeit, the chief reward is not till the last cast, till we come home to heaven. The word here rendered "reward," signifieth the heel, and by a metaphor, the end of a work, and the reward of it, which is not till the end. —John Trapp.