For to which of the angels did God ever say, “You are my Son, today I have begotten you”? Or again, “I will be to him a father, and he shall be to me a son”?
5. Thou art my Son, etc. It cannot be denied but that this was spoken of David, that is, as he sustained the person of Christ. Then the things found in this Psalm must have been shadowed forth in David, but were fully accomplished in Christ.
The apostle, having proved the pre-eminence of the gospel above the law from the pre-eminence of the Lord Jesus Christ above the prophets, now proceeds to show that he is much superior not only to the prophets, but to the angels themselves.
Commenting on Hebrews 1:4-14
For unto which of the angels said he at any time,.... That is, he never said to any of the angels what he has said to Christ; namely, what follows, thou art my Son, this day have I begotten thee for though angels are called the sons of God, Job 1:6 yet are never said to be begotten by him; or, with this clause annexed...