Prayer assumes the sovereignty of God. If God is not sovereign, we have no assurance that He is able to answer our prayers. Our prayers would become nothing more than wishes. But while God's sovereignty, along with his wisdom and love, is the foundation of our trust in Him, prayer is the expression of that trust.
Jerry Bridges (2014). “Holiness Day by Day: Transformational Thoughts for Your Spiritual Journey”, p.105, Tyndale House