For he hath put - God has put by promise, purpose, or decree.
All things under his feet - He has made all things subject to him; or has appointed him to be head over all things; compare Matthew 28:18; John 17:2; Ephesians 1:20-22. It is evident that Paul here refers to some promise or prediction respecting the Messiah, though he does not expressly quote any passage, or make it certain to what he refers. The “words” “hath put all things under his feet” are found in Psalms 8:6, as applicable to “man,” and as designed to show the dignity and dominion of man. Whether the psalm has any reference to the Messiah, has been made a question. Those who are disposed to see an examination of this question, may find it in Stuart on the Hebrews, on Hebrews 2:6-8; and in Excurses ix. of the same work, pp. 568-570. Ed. 1833. In the passage before us, it is not “necessary” to suppose that Paul meant to say that the psalm had a particular reference to the Messiah. All that is implied is, that it was the intention of God to subdue all things to him; this was the general strain of the prophecies in regard to him; this was the purpose of God; and this idea is accurately expressed in the words of the psalm; or these words will convey the “general sense” of the prophetic writings in regard to the Messiah. It may be true, also, that although the passage in Psalms 8:1-9 has no immediate and direct reference to the Messiah, yet it includes him as one who possessed human nature.
The psalm may be understood as affirming that all things were subjected to “human nature;” that is, human nature had dominion and control over all. But this was more particularly and eminently true of the Messiah than of any other man. In all other cases, great as was the dignity of man, yet his control over “all things” was limited and partial. In the Messiah it was to be complete and entire. His dominion, therefore, was a complete fulfillment, that is, “filling up” (πλήρωμα plērōma) of the words in the psalm. Under him alone was there to be an entire accomplishment of what is there said; and as that psalm was to be fulfilled, as it was to be true that it might be said of man that all things were subject to him, it was to be fulfilled mainly in the person of the Messiah, whose human nature was to be exalted above all things; compare Hebrews 2:6-9
But when he saith - When God says, or when it is said; when that promise is made respecting the Messiah.
It is manifest - It must be so; it must be so understood and interpreted.
That he is excepted ... - That God is excepted; that it cannot mean that the appointing power is to be subject to him. Paul may have made this remark for several reasons. Perhaps:
(1) To avoid the possibility of cavil, or misconstruction of the phrase, “all things,” as if it meant that God would be included, and would be subdued to him; as among the pagan, Jupiter is fabled to have expelled his father Saturn from his throne and from heaven.
(2) It might be to prevent the supposition, from what Paul had said of the extent of the Son’s dominion, that he was in any respect superior to the Father. It is implied by this exception here, that when the necessity for the special mediatorial kingdom of the Son should cease, there would be a resuming of the authority and dominion of the Father, in the manner in which it subsisted before the incarnation.
(3) The expression may also be regarded as intensive or emphatic; as denoting, in the most absolute sense, that there was nothing in the universe, but God, which was not subject to him. God was the only exception; and his dominion, therefore, was absolute over all other beings and things.