(Verse 31) - He, seeing this before - By the spirit of prophecy. From this it appears that David had distinct views of the great doctrines pertaining to the Messiah.

Spake  - See Ps. 16.

(Verse 32) - This Jesus - Peter, having shown that it was predicted that the Messiah would rise, now affirms that such a resurrection occurred in the case of Jesus. If it was a matter of prophecy, all objection to the truth of the doctrine was taken away, and the only question was whether there was evidence that this had been done. The proof of this Peter now alleges, and offers his own testimony, and that of his brethren, to the truth of this great and glorious fact.

We are all witnesses - It seems probable that Peter refers here to the whole 120 who were present, and who were ready to attest it in any manner. The matter which was to be proved was that Jesus was seen alive after he had been put to death. The apostles were appointed to bear witness of this. We are told by Paul 1 Cor. 15:6 that he was seen by more than five hundred brethren, that is, Christians, at one time. The 120 assembled on this occasion were doubtless part of the number, and were ready to attest this. This was the proof that Peter alleged; and the strength of this proof was, and should have been, perfectly irresistible:

(1)  They had seen him themselves. They did not conjecture it or reason about it; but they had the evidence on which people act every day, and which must be regarded as satisfactory the evidence of their own senses.

(2)  The number was such they could not be imposed on. If 120 persons could not prove a plain matter of fact, nothing could be established by testimony; there could be no way of arriving at any facts.

(3)  The thing to be established was a plain matter. It was not that they “saw him rise.” That they never pretended: Impostors would have done this. But it was that they saw him, talked, walked, ate, drank with him, being alive, AFTER, he had been crucified. The fact of his death was matter of Jewish record, and no one called it in question. The only fact for Christianity to make out was that he was seen alive afterward, and this was attested by many witnesses.

(4)  They had no interest in deceiving the world in this thing. There was no prospect of pleasure, wealth, or honor in doing it.

(5)  They offered themselves now as ready to endure any sufferings, or to die, in attestation of the truth of this event.

(Verse 33) - Therefore, being by the right hand - The right hand among the Hebrews was often used to denote “power”; and the expression here means, not that he was exalted to the right hand of God. but by his power. He was raised from the dead by his power, and borne to heaven, triumphant over all his enemies. The use of the word “right hand” to denote “power” is common in the Scriptures: (Job 40:14, “Thine own right hand can save thee”; Ps. 17:7, “Thou savest by thy right hand them that trust in thee”; Ps. 18:35; 20:6; 21:8; 44:3; 60:5, etc).

Exalted - Constituted King and Messiah in heaven. Raised up from his condition of humiliation to the glory which he had with the Father before the world was, (John 17:5).

And having received  - The Holy Spirit was promised to the disciples before his death, (John 14:26; 15:26; 16:13-15). It was expressly declared:

(1)  That the Holy Spirit would not be given except the Lord Jesus should return to heaven John 16:7; and,

(2)  That this gift was in the power of the Father, and that he would send him, (John 14:26; 15:26). This promise was now fulfilled, and those who witnessed the extraordinary scene before them could not doubt that it was the effect of divine power.

Hath shed forth this  - This power of speaking different languages and declaring the truth of the gospel. In this way Peter accounts for the remarkable events before them. What had occurred could not be produced by new wine, (Acts 2:15). It was expressly foretold, (Acts 2:16-21). It was predicted that Jesus would rise, (Acts 2:22-31). The apostles were witnesses that he had risen, and that he had promised that the Holy Spirit would descend; and the fulfillment of this promise was a rational way of accounting for the scene before them. It was unanswerable; and the effect on those who witnessed it was such as might be expected.

(Verse 34-35) - For David is not ascended into the heavens - That is, David has not risen from the dead and ascended to heaven. This further shows that Ps. 16 could not refer to David, but must refer to the Messiah. Great as they esteemed David, and much as they were accustomed to apply these expressions of the Scripture to him, yet they could not be applicable to him. They must refer to some other being; and especially that passage which Peter now proceeds to quote. It was of great importance to show that these expressions could not apply to David, and also that David bore testimony to the exalted character and dignity of the Messiah. Hence, Peter here adduces David himself as affirming that the Messiah was to be exalted to a dignity far above his own. This does not affirm that David was not saved, or that his spirit had not ascended to heaven, but that he had not been exalted in the heavens in the sense in which Peter was speaking of the Messiah.

But he saith himself - Ps. 110:1.

The LORD - The small capitals used in translating the word “LORD” in the Bible denote that the original word is the proper name for God - YAHWEH. The Hebrews regarded this as the unique name of God, a name incommunicable to any other being. It is not applied to any being but God in the Scriptures. The Jews had such a reverence for it that they never pronounced it; but when it occurred in the Scriptures they pronounced another name, Adonai.  Here it means, “Yahweh said,” etc.

My Lord - This is a different word in the Hebrew - it is the Adonai we mentioned above. It properly is applied by a servant to his master, or a subject to his sovereign, or is used as a title of respect by an inferior to a superior. It means here, “Yahweh said to him whom I, David, acknowledge to be my superior and sovereign.” Thus, though he regarded him as his descendant according to the flesh, yet he regarded him also as his superior and Lord. By reference to this passage our Saviour confounded the Pharisees, (Matt. 22:42-46). That the passage in this Psalm refers to the Messiah is clear. Our Saviour, in (Matt. 22:42), expressly applied it thus, and in such a manner as to show that this was the well-understood doctrine of the Jews. (See Matt. 22:42, etc).