Hebrews 1:5

Which of the angels. Now begins a series of OT quotations to prove the superiority of Christ over the angels. The anticipated answer to the question is, “He never said this to an angel at any time.”

Thou art my Son. A citation from Ps. 2:7 (see comment there). For a discussion of the title “Son” applied to Christ see on Luke 1:35; cf. on Rom. 1:4. The author here disposes of the claim made by some that Christ is an angel raised to a higher position. If Christ really were an angel elevated to His present status, then God did say to an angel, “Thou art my Son.” But God did not say this to any angel “at any time.” Some refer to Job 1:6; 2:1; 38:7 as evidence that the Scriptures do call angels sons of God (see comments on these verses). It should be noted that these expressions are all in the plural. Nowhere is any angel called a son of God; and, of course, angels are created beings (Col. 1:16).

This day have I begotten thee. For a discussion of the various interpretations given to this passage see on Acts 13:33; cf. on Rom. 1:4.

I will be to him a Father. A citation from 2 Sam. 7:14 (see comment there). The original prophecy had primary application to Solomon, but it is here given Messianic import. The purpose of the citation is to highlight the sonship of Christ and thus further establish His superiority over the angels.