1 Corinthians 15:51

Behold, I show you a mystery
Or a secret, which could never have been discovered by reason, or the light of nature, and what is of pure revelation; and which perhaps the apostle became acquainted with, when he was caught up into the third heaven; and is what is never made mention of by any prophet, or apostle, but himself: he prefaces the account of it in this manner, partly to show the great respect he had for these Corinthians, that he treated them as his bosom friends, to whom he communicated his secrets; and partly to excite their curiosity and attention:

we shall not all sleep, but we shall all be changed;
some copies read, "we shall all rise again, but we shall not all be changed", and so the Vulgate Latin version; according to which the sense is, all will rise again, both just and unjust, but all will not be changed into a state of glory; but the apostle is only speaking of the saints, of whom it is true, not only that they shall rise again, but shall be changed from corruption to incorruption; wherefore this cannot be a true reading: others read the words thus, "we shall all die, but we shall not all be changed"; and so the Ethiopic version and the Alexandrian copy seem to have read; which is just the reverse of the text, and arises from a wrong sense of ( Hebrews 9:27 ) where it is not said, it is "appointed unto all men", but "unto men once to die"; from which rule there has been some exceptions, as the instances of Enoch and Elijah show; and there will be more at the time of Christ's coming, for all will not sleep in their graves, or die, for death is meant by sleeping; they will not die as men ordinarily do, and continue under the power of death, but they will be changed at once from corruption to incorruption, from dishonour to glory, from weakness to power, from being natural to be spiritual bodies; this change all the saints will undergo, whether dead or alive, at Christ's coming; the dead by a resurrection from the dead, and the living by a secret and sudden power, which will at once render their bodies, without separating them from their souls, immortal and glorious: and this reading and sense are confirmed by the Syriac and Arabic versions.