Here are some good quotes to encourage us to pray:
Robert L. Dabney: “Prayer is the vital breath of religion in the soul. It cultivates our sense of dependence and of God’s sovereignty. By confessing our sins, the sense of sin is deepened. By rendering thanks, gratitude is enlivened. By adoring the divine perfections, we are changed into the same image, from glory to glory. From all this it is apparent that prayer is the Christian’s vital breath. If God had not required it, the Christian would be compelled to offer it by his own irrepressible promptings …. To have no prayer is, for man, to have no religion” (Syllabus and Notes of the Course of Systematic and Polemic Theology Taught in Union Theological Seminary, Virginia [Edinburgh: Banner of Truth Trust, 1985], p. 716).
Alexander Comrie: “Faith, abiding in Christ so as to bring forth fruit, makes the soul to abide continually more earnest in prayer, or in crying, and lifting up of the heart unto the Lord. This is Paul’s sweet exhortation: ‘Pray without ceasing’ (1 Thess 5:17) … Prayer is not only the breath, but also a singular sustainer of the life of faith; the stronger in faith, the more fervent in prayer” (The ABC of Faith [trans. J. Marcus Banfield; W. Yorks, Great Britain: Zoar Publications ,1978], p. 81).
Charles Hodge: “It would be a great mistake, if a Christian should act on the assumption that the life of God in his soul could be adequately preserved by that form of prayer, which consists in habitual communion with God. The believer needs, in order to maintain his spiritual health and vigour, regular and stated seasons of prayer, as the body needs its daily meals .... We read that Christ often retired for the purpose of prayer, and not unfrequently spent whole nights in that exercise. If the spotless soul of Jesus needed these seasons of converse with God, none of his followers should venture to neglect this important means of grace” (Systematic Theology [London and Edinburgh: Thomas Nelson and Sons/New York: Charles Scribner and Co., 1873], 3.705-6).