Men and brethren - This is a customary mode of address, implying affection and respect, Acts 13:26. The Syriac renders it more appropriately than by the introduction of the conjunction “and” - “Men, our brethren.”
This scripture - This prediction contained in the writings of the Old Testament. Compare the notes on John 5:39. The passage to which Peter refers is commonly supposed to be that recorded in Psalms 41:9, “Yea, mine own familiar friend ...hath lifted up his heel against me.” This is expressly applied to Judas by our Saviour, in John 13:18. But it seems clear that the reference is not to the 41st Psalm, but to the passage in the 69th Psalm which Peter proceeds to quote in Acts 1:20.
Must needs have been fulfilled - It would certainly be fulfilled. Not that there was any physical necessity or any compulsion; but it could not but occur that a prediction of God would be fulfilled. This makes no affirmation about the freedom of Judas in doing it. A man will be just as free in wickedness if it be foretold that he will be wicked, as if it had never been known to any other being but himself.
The Holy Ghost ... - This is a strong attestation to the inspiration of David, and accords with the uniform testimony of the New Testament, that the sacred writers spake as they were moved by the Holy Spirit, 2 Peter 1:21.
Concerning Judas - In what respect this was concerning Judas, see Acts 1:20.
Which was guide ... - Matthew 26:47; John 18:3.