He has granted to us his precious and very great promises.
2 Peter 1:4
Faith may act with great advantage upon the promises of God and gain encouragement from them. There are promises suitable for every condition. Not only are there express promises, there are also promises that can be applied by faith. The titles of God are virtual promises. He is a shield, a strong tower, a hiding place, and our portion. Faith may apply these as promises. Scriptural assertions may also be applied as promises: ‘The fruit of the Spirit is love, joy, peace, patience…’ (Gal. 5:22). Faith may conclude that the Spirit will bring forth this fruit in me. What God has done for his people formerly are, inn effect, promises too. Faith may conclude that the Lord will work in like manner in the future. If he delivered others who trusted in him, he will deliver me if I trust in him now. He is the same yesterday and forever. David conquered Goliath in the name of the Lord, and prevailed. If I go in like manner against my lusts, I shall prevail. The prayers of God’s people and the commandments of God are also virtual promises. We are commanded to forgive seventy times seven, so, faith may conclude, the Lord will forgive much more. Even in threatenings we might find a promise. If the wicked shall be turned into hell, faith may conclude that the godly shall be carried into heaven.
Gather the promises and meditate on them. They are meat in this wilderness. Often be mining their treasures. Do not allow these pearls to lie neglected in the field. Treasure them up. Fill your memories with them. A promise treasured will afford comfort in our callings, dungeons, and banishments. Meditate frequently and seriously on them. Meditation squeezes the sweetness out of them and helps us to unite our faith to them for encouragement.
David Clarkson, Works, 1:187-189