Charles H. Spurgeon on Psalms 116:9

Return unto thy rest, O my soul. . . . I will walk. How can these two stand together? Motus et quies private opponuntur, saith the philosopher, motion and rest are opposite; now walking is a motion, as being an act of the locomotive faculty. How then could David return to his rest and yet walk? You must know that walking and rest here mentioned, being of a divine nature, do not oppose each other; spiritual rest maketh no man idle, and therefore it is no enemy to walking; spiritual walking maketh no man weary, and therefore it is no enemy to rest. Indeed, they are so far from being opposite that they are subservient to each other, and it is hard to say whether that rest be the cause of this walking, or this walking a cause of that rest. Indeed, both are true, since he that rests in God cannot but walk before him, and by walking before, we come to rest in God. Returning to rest is an act of confidence, since there is no rest to be had but in God, nor in God but by believing affiance in, and reliance on him. Walking before God is an act of obedience;when we disobey we wander and go astray, only by obedience we walk. Now these two are so far from being enemies, that they are companions and ever go together; confidence being a means to quicken obedience, and obedience to strengthen confidence. Nathaniel Hardy.