John Calvin Commentary Hebrews 9:27

"And inasmuch as it is appointed unto men once to die, and after this [cometh] judgment;" — Hebrews 9:27 (ASV)

And as it is appointed, etc. The meaning is this: since we patiently wait after death for the day of judgment, this being the common lot of nature against which it is not right to struggle, why should there be less patience in waiting for the second coming of Christ?

For if a long interval of time does not diminish, for humans, the hope of a happy resurrection, how unreasonable would it be to render less honor to Christ? But it would be less honor if we were to call upon him to undergo a second death, since he has already died once.

If anyone were to object and say that some, such as Lazarus, had died twice and not once, the answer would be this—the Apostle speaks here of the ordinary lot of men; but those who will by an instantaneous change put off corruption (1 Corinthians 15:51) are to be excepted from this condition, for he includes only those who wait for a long time in the dust for the redemption of their bodies.