Prayer is an offering that belongs to God and is acceptable to him: it is the offering he has asked for, the offering he planned as his own. We must dedicate this offering with our whole heart, we must fatten it on faith, tend it by truth, keep it unblemished through innocence and clean through chastity, and crown it with love.

Prayer gives the armor of patience to those who suffer, who feel pain, who are distressed. It strengthens the power of grace, so that faith may know what it is gaining from the Lord, and understand what it is suffering for the name of God. Prayer is the one thing that can conquer God. But Christ has willed that it should work no evil, and has given it all power over good. What more need be said on the duty of prayer? Even the Lord himself prayed. To him be honor and power for ever and ever.

—Tertullian, On Prayer, 28-29