Your fathers did eat manna— Our Lord next drew a comparison between himself, considered as the bread from heaven, and the manna which Moses provided for their fathers in the desart, and which they admired so greatly. "Those who thus regard me," said he, "as the bread of life, will receive far more important blessings than Moses, of whom you have now been boasting, could possibly give: for though indeed your fathers, under the conduct of that illustrious prophet, did eat manna in the wilderness; yet it was not sufficient to maintain their spiritual or temporal life; they are long since dead: but this of which I now speak, is the true bread which cometh down from heaven, and is of such a nature, that any one may eat of it, and have his life so nourished and supported by it, that he shall not die, but be assuredly delivered from the condemnation and ruin to which the breach of God's righteous law has subjected every offender." The opposition between και απεθανον, and are dead, in John 6:49 and μη αποθανη, may not die, in John 6:50 is elegant, and shews that in the former the spiritual death is meant, as well as in the latter.
Related Commentaries of John 6:49
John 6:49-50
49 Your fathers did eat manna in the wilderness, and are dead.
50 This is the bread which cometh down from heaven, that a man may eat thereof, and not die.