John Chrysostom

Still I should like to ask our objectors, what means that which is said by the Prophet, "Before Me there was no God formed, nor is there any after Me"? For if the Son is younger than the Father, how, says He, "Nor is there any after me"? Will you take away the being of the Only-Begotten Himself? You either must dare this, or admit one Godhead with distinct Persons of the Father and Son.

Homilies On The Gospel Of John 4 ↗

Jerome

You are my witnesses, says the Lord, and my servant whom I have chosen, that you may know and believe me, and understand that I am he. Before me no god was formed, nor shall there be any after me. I am, I am the Lord, and there is no savior without me. LXX: Be my witnesses, and I am a witness, says the Lord God, and my servant whom I have chosen, so that you may know and believe and understand that I am: Before me there was no other God and after me there will be none. I am God, and there is no Savior besides me. …

Commentary on Isaiah ↗

Thomas Aquinas

He gives testimony, assigning men to give testimony: you are my witnesses, my servant, the people of Jacob, or Christ: you shall be witnesses (Acts 1:8); setting out the manner of knowing: that you may know, as to those things which can be known about God by natural reason, and believe, as to those things which are above reason, and thus, understand, for unless you believe, you will not understand, above (Isa 7:9), according to another reading; and setting out what is said by the witnesses, that he alone is God: that I, alone, am, …

Commentary on Isaiah ↗