Albert Barnes' Notes on the Whole Bible - John 6:62
What and if ... - Jesus does not say that those who were then present would see him ascend, but he implies that he would ascend. They had taken offence because he said he came down from heaven. Instead of explaining that away, he proceeds to state another doctrine quite as offensive to them - that he would reascend to heaven. The apostles only were present at his ascension, Acts 1:9. As Jesus was to ascend to heaven, it was clear that he could not have intended literally that they should eat... read more
The Pulpit Commentary - John 6:62
The Ascension foretold. The aim of our Lord's conversation with the Jews was to convince those who were prepared for the revelation, that he was the Divine Mediator, and that union with him was the one hope of salvation for sinful men. An inferior claim he could not have made. Yet this assertion of his power and dignity was an offence to many who heard the Saviour's language, and who could not believe that the lowly Nazarene occupied a place so exalted in the counsels of the Eternal.... read more