The Father of the OT and NT is God. God is so awesome of a being that when he speaks, his words are alive. Like a hand attached to a body, the hand is part of the body. The Father's words are like a hand [,part of his body] and exerting all of the authority of the Father. So if Jesus is the Word of God, and God is so awesome that his words are alive, then the word of God has ALL of the authority of God.
That's how I see it without getting too technical and philosophical.