Here the prophet is talking about spiritual things, because the rest found is soul rest.
D. J. Evans tells of his experience in a deep coal mine where he once worked. All his companions had left him. Suddenly his lamp fell and went out. He was in utter darkness, and his only hope was in finding some sure guide to the shaft. As he groped in the dark his feet struck the rails on which the coal cars ran. Cautiously, but with many a stumble, he hobbled along, keeping one foot sliding on the rail. He could see nothing, but he could feel the rail. At long last he reached the foot of the shaft and sent up a signal for a cage. Soon he was lifted to the surface and walked out into the glorious sunlight, which showed him the road home. Trusting those tracks in the darkness, he found the lighted way at last.
God has laid down spiritual, moral guides for us to follow, and these guides, like the rails in the mine, lead to the light. Even in the darkness they bring soul rest, for we know that we are on the right way. Our Savior said, "I am the way, the truth, and the life" (John 14:6). The Holy Scriptures reveal the Lord Jesus as the true, eternal way of righteousness. He was before all time, "whose goings forth have been from of old, from everlasting" (Micah 5:2). When we seek the old way, the original way, we seek the true way, the truth itself as it is in Jesus. The good way, the true way, the old way, may lead through darkness, but it always leads upward at last to the light. But seeing the good way, recognizing it, knowing it, even loving it, is not enough. We must "walk therein." Obedience is the response of faith.
MEDITATION PRAYER: "Teach me thy way, O Lord, and lead me in a plain path, because of mine enemies" (Ps. 27:11).