Grant me your grace, most merciful Jesus, that your grace may be with me, work in me, and continue with me to the end.
Grant me always to want and desire whatever is most acceptable to you and pleases you best.
Let your will be mine, and let my will always follow yours and agree perfectly with it.
Let there be between you and me but one will, so that I may love what you love and abhor what you hate. Grant that I may die to all things that are in the world and, for your sake, love to be despised, and not to be known by the world. Grant that I may rest in you above all other things, and that my heart may be at peace in you.
You are the true peace of the heart. You are its only rest. Outside of you, all things are hard and uneasy.
In this peace, the same peace that is in you, the one sovereign eternal Good, I will sleep, and I will rest. Amen.
Source: Thomas à Kempis, Imitation of Christ, Book 3
Source of this version: Modified from http://catholictradition.org/war-time4.htm
Also found in The Oxford Book of Prayer, ed. Appleton, © 1985, 1992
The last paragraph may be a reference or quote of Psalm 4:8.