Charles Ellicott Commentary John 5:28

"Marvel not at this: for the hour cometh, in which all that are in the tombs shall hear his voice," — John 5:28 (ASV)

Marvel not at this—that is, that He Himself has a source of life and authority to judge. There will follow from this “greater works,” at which they will marvel.

There is an hour coming (here not with the addition and now is, of John 5:25) when the victory over physical death will also make manifest this life, for all that are in the graves shall hear His voice, and the final judgment will declare to the universe His authority to judge.