“Jesus saith unto them, Come and dine. And none of the disciples durst ask him, Who art thou? knowing that it was the Lord.”
John 21:12 — Greek Interlinear
Church Fathers on John 21:12
John does not say that He ate with them, but Luke does. He ate however not to satisfy the wants of nature, but to show the reality of His resurrection.
The bodies of the just, when they rise again, shall need neither the word of life that they die not of disease, or old age, nor any bodily nourishment to prevent hunger and thirst. For they shall be endowed with a sure and inviolable gift of immortality, that they shall not eat of necessity, but only be able to eat if they will. Not the power, but the need of eating and drinking shall be taken away from them; in like manner as our Savior after His resurrection took meat and…
By holding this last feast with seven disciples, he declares that they only who are full of the sevenfold grace of the Holy Spirit, shall be with Him in the eternal feast. Time also is reckoned by periods of seven days, and perfection is often designated by the number seven. They therefore feast upon the presence of the Truth in that last banquet, who now strive for perfection.