56 The divine High Priest wished us to have abundant witness to His own most perfect obedience to the Eternal Father; for this reason both the Prophecies and the Gospels often testify to the entire submission of the Son of God to the will of the Father. "When He cometh into the world He saith; sacrifice and oblation Thou wouldst not: but a body Thou has fitted to Me. . .Then said I: Behold I come. In the head of the book it is written of Me that I should do Thy will, O God. . ." "My meat is to do the will of Him that sent Me." On His very cross He consecrated obedience. He did not wish to commit His soul into the hands of His Father before having declared that all was fulfilled in Him that the Sacred Scriptures had foretold; He had accomplished the entire charge entrusted to Him by the Father, even to the last deeply mysterious "I thirst," which He pronounced "that the Scripture might be fulfilled." By these words He wished to show that zeal even the most ardent ought always to be completely subjected to the will of the Father; that our zeal should always be controlled by obedience to those who for us, have the place of the Father, and convey to us His will, in other words our lawful Superiors in the Hierarchy.
Source: Ad Catholici Sacerdotii (Vatican.va)