Jesus spoke the gospel, which is the voice of God, because His created existence is called the "Word". The Word is spoken through all God's servants called the prophets and saints because we're one in the mind of God.
John 1
1: In the beginning was the Word, and the Word was with God, and the Word was God.
2: He was in the beginning with God;
3: all things were made through him, and without him was not anything made that was made.
4: In him was life, and the life was the light of men.
Ephesians 1
1: Paul, an apostle of Christ Jesus by the will of God, To the saints who are also faithful in Christ Jesus:
2: Grace to you and peace from God our Father and the Lord Jesus Christ.
3: Blessed be the God and Father of our Lord Jesus Christ, who has blessed us in Christ with every spiritual blessing in the heavenly places,
4: even as he chose us in him before the foundation of the world, that we should be holy and blameless before him.
5: He destined us in love to be his sons through Jesus Christ, according to the purpose of his will,
9: For he has made known to us in all wisdom and insight the mystery of his will, according to his purpose which he set forth in Christ
10: as a plan for the fulness of time, to unite all things in him, things in heaven and things on earth.
11: In him, according to the purpose of him who accomplishes all things according to the counsel of his will,
12: we who first hoped in Christ have been destined and appointed to live for the praise of his glory.
13: In him you also, who have heard the word of truth, the gospel of your salvation, and have believed in him, were sealed with the promised Holy Spirit,
Romans 9:
28: We know that in everything God works for good with those who love him, who are called according to his purpose.
29: For those whom he foreknew he also predestined to be conformed to the image of his Son, in order that he might be the first-born among many brethren.
30: And those whom he predestined he also called; and those whom he called he also justified; and those whom he justified he also glorified.
These scriptures are testimonies by the messenger within us, who has us (the glorified flesh) speak for our Creator.
I Corinthians 2:
7: But we impart a secret and hidden wisdom of God, which God decreed before the ages for our glorification.
8: None of the rulers of this age understood this; for if they had, they would not have crucified the Lord of glory.