1 Corinthians 15:5

5.That he was seen by Cephas He now brings forward eye witnesses, ( αὐτόπτας ) as they are called by Luke, (Luke 1:2,) who saw the accomplishment of what the Scriptures had foretold would take place. He does not, however, adduce them all, for he makes no mention of women. When, therefore, he says that he appeared first to Peter, you are to understand by this that he is put before all the men, so that there is nothing inconsistent with this in the statement of Mark (Mark 16:9) that he appeared to Mary.

But how is it that he says, that he appeared to the twelve, when, after the death of Judas, there were only eleven remaining? Chrysostom is of opinion that this took place after Matthias had been chosen in his room. Others have chosen rather to correct the expression, looking upon it as a mistake (15) But as we know, that there were twelve in number that were set apart by Christ’s appointment, though one of them had been expunged from the roll, there is no absurdity in supposing that the name was retained. On this principle, there was a body of men at Rome that were called Centumviri, (16) while they were in number 102. (17) By the twelve, therefore, you are simply to understand the chosen Apostles.

It does not quite appear when it was that this appearing to more than five hundred took place. Only it is possible that this large multitude assembled at Jerusalem, when he manifested himself to them. For Luke (Luke 24:33) makes mention in a general way of the disciples who had assembled with the eleven; but how many there were he does not say. Chrysostom refers it to the ascension, and explains the word ἐπάνω to mean, from on high. (18) Unquestionably, as to what he says in reference to his having appeared to James apart, this may have been subsequently to the ascension.

By all the Apostles I understand not merely the twelve, but also those disciples to whom Christ had assigned the office of preaching the gospel. (19) In proportion as our Lord was desirous that there should be many witnesses of his resurrection, and that it should be frequently testified of, let us know that it should be so much the more surely believed among us. (Luke 1:1.) Farther, inasmuch as the Apostle proves the resurrection of Christ from the fact that he appeared to many, he intimates by this, that it was not figurative but true and natural, for the eyes of the body cannot be witnesses of a spiritual resurrection.