John Chrysostom

And again he saith: "Thou Lord in the beginning hast laid the foundation of the earth, and the heavens are the works of Thine hands. They shall perish, but Thou remainest, and they shall all wax old as a garment, and as a vesture shalt Thou fold them up, and they shall be changed: but Thou art the same and Thy years shall not fail." Lest hearing the words, "and when He bringeth in the First-Begotten into the world"; thou shouldest think it as it were a Gift afterwards super-added to Him; above, he both corrected this beforehand, and …

Homily on Hebrews 3 ↗

Theophylact of Ohrid

Lest you, hearing the words "when He brings the Firstborn into the world," should think that this is a gift given to Him afterwards by the Father, he now shows that He is the Creator of the world not in recent times, but from of old. This is also against Paul of Samosata, and affirms that Christ existed before Mary, since He is the Creator of creation. And against Arius, who considered Him an assistant or rather an instrument, since it was said above: "through Whom He also made the ages" (Heb. 1:2). Here He is presented as Creator. …

Commentary on Hebrews ↗

Oecumenius

"And you, O Lord, laid the foundation of the earth in the beginning." For when he again brings in the Firstborn; that is, when the Father was pleased to reveal His Firstborn Son in the flesh to those who dwell in the world. For it says: And the angels came and ministered to him (Matt. 4:11); and you will see the angels descending upon the Son of Man (Jn. 1:51) from now on.

The Pseudo-Oecumenian Catena on Hebrews ↗

Thomas Aquinas

67. – Above, the Apostle mentioned four things in which Christ excelled the angels, and he proved two of them, namely, that He excels them, because He is the Son and because He is the heir. Now he proves the third, namely, that He excels them in His power of acting, because through Him the Father made the world. But the Apostle proves this on the authority of the same prophet. …

Commentary on Hebrews ↗