John Chrysostom — as excerpted in the Catena Aurea on John 20:26-31

“(Hom. lxxxvii. 1) Jesus then comes Himself, and does not wait till Thomas interrogates Him. But to shew that He heard what Thomas said to the disciples, He uses the same words. And first He rebukes him; Then saith He to Thomas, Reach hither thy finger, and behold My hands; and reach hither thy hand, and thrust it into My side: secondly, He admonishes him; And be not faithless, but believing. Note how that before they receive the Holy Ghost faith wavers, but afterward is firm. We may wonder how an incorruptible body could retain the marks of the nails. But it was done in condescension; in order that they might be sure that it was the very person Who was crucified.”