The following is an excerpt from Johannes Brenz’ Commentary on St. John (1532).
HE WILL NOT SPEAK FROM HIMSELF [Jn 15:13]
This means that the Spirit will teach nothing new, but will reveal the Word from My Father, which I am now predicting beforehand. He will disclose the Word of the Father that He heard from the Father, for He is the eternal Spirit of the Father. “He will declare the things that are to come,” that is hidden things. These are that the Gospel must be spread among the nations, that the cross is the way and glory, that faith is true righteousness, etc. For it was not spoken about the Spirit of the Prophets, although the Apostles did not lack this Spirit, who is a unique gift. That Spirit does not justify, but the Spirit of faith justifies. By this Spirit we understand that sin, death, and hell is conquered through Christ, and also that the same victory is common to all of us, whether Jew or Gentile.
HE WILL GLORIFY ME ETC. [Jn 15:14]
Because afterwards the Holy Spirit will be revealed, you will preach the Gospel, even My glorious victory over the world, sin, cross, death, Satan, and hell, in the whole wide world, and you will announce it everywhere to the Gentiles, since this results in the greatest glory for My name.
HE WILL RECEIVE FROM ME. [Jn 15:15]
For I Myself am the Word from the Father. Therefore, whenever the Word is revealed, He will receive it from Me. This means that He will make known My Word, which I have taught, but, more than that, I am that very Word. But when He says, “He will receive from Me,” He adds the reason for this, when He says, “All that the Father has is Mine.” It’s as if He said, “All the good things that the Father has, have been imprinted on Me from eternity, even the Holy Spirit in same measure. This Spirit, who is the Father’s Spirit, has been made Mine from eternity. For this reason it is not absurd that I’ve said, ‘He will receive from Me.’ Because He is both Mine and the Father’s.”