John 20:26

And after eight days
That is, after another week, the same day a week later, which taking in the day in which Christ rose and appeared to Mary Magdalene, and his disciples, and the day in which he now appeared to the disciples with Thomas, made eight days; a like way of speaking see in ( Luke 9:28 ) compared with ( Matthew 17:1 ) . And Dr. Hammond has proved from Josephus ^F23, that the Jews used to express a week by eight days.

Again, his disciples were within;
within doors, in some private house; probably the same as before, in some part of the city of Jerusalem:

and Thomas with them:
which shows their harmony and agreement, their frequency and constancy in meeting together, and their Christian forbearance with Thomas, notwithstanding his unbelief; whom they looked upon as a good man, and retained in their company, hoping by one means or other he would be convinced: and it also shows Thomas's regard to them, and affection for them, by meeting with them, though he had not the same faith in the resurrection of Christ:

then came Jesus;
when the disciples, with Thomas, were together; so making good his promise to meet with his people when they meet; and thereby putting an honour upon, and giving encouragement to with the saints: if it should be asked, why did not Christ come sooner? it may be replied, that the reason, on his part, was, it was his will and pleasure to come at this time, and not before; Christ has his set times to himself, when he will appear and manifest himself to his people: on Thomas's part the reasons might be, partly to rebuke him for his sin, and that the strength of his unbelief might appear the more, and that some desire might be stirred up in him to see Christ, if he was risen. And on the part of the disciples, because they did not meet together sooner; and for the further trial of their faith, whether it would continue or not, Thomas obstinately persisting in his unbelief:

the doors being shut;
as before, and for the same reason, for fear of the Jews, as well as for the privacy of their devotion and conversation:

and stood in the midst;
having in the same powerful manner as before caused the doors, locks, and bars to give way, when at once he appeared in the midst of them all, not to Thomas alone, but to all the eleven; and this the rather, because the disciples had bore a testimony to Christ's resurrection, and which he meant now to confirm; and to rebuke Thomas publicly, who had sinned before them all:

and said, peace be unto you;
which he had said before, and now, saluting Thomas in like manner as he did the rest, notwithstanding his unbelief.