Roman Catechism 37.10

Chapter 37 — Part IV: Prayer — The Third Petition: Thy Will Be Done on Earth as It Is in Heaven

Section 10. Now this is what we ask when we address to God these words: Thy will be done. We fell into this state of misery by disobeying and despising the divine will. God vouchsafes to propose to us, as the sole corrective of such great evils, a conformity to His will, which by sinning we despised; He commands us to regulate all our thoughts and actions by this standard. Now it is precisely His help to accomplish this that we ask when we suppliantly address to God the prayer, Thy will be done.