6 Because then I was speaking of what I had brought forward, “And I knew,” says He, “that His commandment is everlasting life.” Mark, Brethren, what I am saying; “I know that His commandment is everlasting life.” And we read in the same John concerning Christ, “He is The True God and Everlasting Life.” If the Father's commandment is “everlasting Life,” and Christ the Son Himself is “everlasting Life;” the Son is Himself the Father's Commandment. For how is not That the Father's Commandment, which is the Father's Word?
Or if you take the commandment given to the Son by the Father in a carnal sense, as if the Father said to the Son, “I command You this, I wish You to do that;” in what words spoke He to the Only Word? When He gave commandment to the Word, did He look for words? That the Father's Commandment then is “Life everlasting,” and that the Son Himself is “Life everlasting,” believe and receive, believe and understand, for the Prophet says, “Unless ye believe you shall not understand.” Do you not comprehend?
Be enlarged. Hear the Apostle: “Be enlarged, bear not the yoke with unbelievers.” They who will not believe this before they comprehend, are unbelievers. And because they have determined to be unbelievers, they will remain in their ignorance. Let them believe then that they may understand. Most certainly the Father's Commandment is “everlasting Life.” Therefore the Father's Commandment is the Very Son who was born this day; a Commandment not given in time but a Commandment Born. The Gospel of John exercises our minds, refines and uncarnalizes them, that of God we may think not after a carnal but a spiritual manner. Let so much then, Brethren, suffice you; lest in length of disputation, the sleep of forgetfulness steal over you.
Source: Sermons on Selected Lessons of the New Testament (New Advent)