John Calvin Commentary Acts 13:34

"And as concerning that he raised him up from the dead, now no more to return to corruption, he hath spoken on this wise, I will give you the holy and sure [blessings] of David." — Acts 13:34 (ASV)

That he should not return. He now adds the other part: that Christ was once raised from death to live forever, as Paul teaches (Romans 6:10):

He dieth no more, neither shall death have dominion over him any more; because he liveth unto God.

For the hope we derive from Christ’s resurrection would be slender and cold if he were still subject to destruction or to any change. Therefore, he is said to have entered into the kingdom of God, so that he might also give his people eternal blessedness, living forever. Because Christ rose for our sake rather than for his own, the perpetual life which the Father has given him extends to us all and is ours.

Nevertheless, the passage from Isaiah cited here, I will give you the holy things of David (Isaiah 55:3), seems to offer little proof of Christ’s immortality. But it is not so. For since Isaiah speaks of the redemption promised to David and affirms that it will be firm and stable, we rightly gather from this the immortal kingdom of Christ, on which the eternity of salvation is grounded.

And Paul followed the Greek interpreters when he used holy things for mercies. Chessed, which signifies meek, merciful, and gentle, is usually translated by the Greeks as holy. Therefore, they translated הסדי of David as the holy things of David, whereas the prophet actually means the grace promised to David.

But Paul conceded this to the ignorant and weak, who were more familiar with the Greek reading, especially since the strength of the testimony lies in another point. For, in summary, this is Paul’s meaning: if the grace is eternal which God says he will give in his Son, the life of his Son must be eternal and not subject to corruption. For we must hold to this rule: that all the promises of God are in Christ yea and amen (2 Corinthians 1:20), and therefore they can have no force unless he gives them life.