56 This should be kept in mind, in particular: whatever a priest may plan, resolve, or do to become holy, he will have to draw, for example and for heavenly strength, upon the Eucharistic Sacrifice which he offers, just as the Roman Pontifical urges: "Be aware of what you are doing; imitate what you hold in your hands."
Source: Sacerdotii Nostri Primordia (Vatican.va)