There is no power in the work itself

Secondly, before you use any means, let it be deeply impressed upon your soul. There is no power in this. It is in itself a poor, dead, empty thing. Separate from God, it is a dry leaf, a shadow. Neither is there any merit in my using this, nothing intrinsically pleasing to God, nothing by which I deserve any favor at his hands, no, not a drop of water to cool my tongue. But because God bids, therefore I do. Because he directs me to wait in this way, therefore here I wait for his free mercy, from which comes my salvation.

Settle this in your heart, that the old Latin phrase opus operatum, the mere work done, profits nothing. There is no power to save but in the Spirit of God, no merit but in the blood of Christ. Consequently, even what God ordains conveys no grace to the soul, if you do not trust in him alone. On the other hand, he who does truly trust in him cannot fall short of the grace of God, even though he were cut off from every outward ordinance, even though he were shut up in the center of the earth.