John Calvin on Romans 6:9

9. Death no more rules over him, etc. He seems to imply that death once ruled over Christ; and indeed when he gave himself up to death for us, he in a manner surrendered and subjected himself to its power; it was however in such a way that it was impossible that he should be kept bound by its pangs, so as to succumb to or to be swallowed up by them. He, therefore, by submitting to its dominion, as it were, for a moment, destroyed it for ever. Yet, to speak more simply, the dominion of death is to be referred to the state of death voluntarily undergone, which the resurrection terminated. The meaning is, that Christ, who now vivifies the faithful by his Spirit, or breathes his own life into them by his secret power from heaven, was freed from the dominion of death when he arose, that by virtue of the same dominion he might render free all his people.