Charles Ellicott Commentary John 20:26

"And after eight days again his disciples were within, and Thomas with them. Jesus cometh, the doors being shut, and stood in the midst, and said, Peace [be] unto you." — John 20:26 (ASV)

And after eight days again his disciples were within.—This refers to the octave of His first appearance to them, or, as we would say today, the first Sunday after Easter. We should not assume that they had failed to meet during the interval, nor that this particular meeting was a special observance of the Lord’s Day. At the same time, this appearance on the recurrence of the first day of the week would take its place among the steps by which the disciples transitioned from the observance of the Jewish Sabbath to that of the Christian Sunday.

The place is obviously the same as that of the first appearance, and the doors are shut for the same reason. (Compare to the note on John 20:19.)

The repetition of the greeting, “Peace be unto you,” is partly the natural salutation as He appears to them. But it is now indeed full of a new meaning, which the thoughts of the week must have written on their hearts. And partly, too, it is perhaps specially intended to include Thomas, who was not present when it was spoken before.