Roman Catechism 35.6

Chapter 35 — Part IV: Prayer — The First Petition: Hallowed Be Thy Name

Section 6. To enable the faithful to understand still more clearly the force and bearing of these Petitions, the pastor should take care to point out to them that the words, On earth as it is in heaven, may be understood of each of the first three Petitions, as follows: Hallowed be thy name on earth as it is in heaven; Thy kingdom come on earth as it is in heaven; and, Thy will be done on earth as it is in heaven.