Albert Barnes Commentary Matthew 24:13

"But he that endureth to the end, the same shall be saved." — Matthew 24:13 (ASV)

He that shall endure unto the end—shall be saved. The word "end" here has by some been thought to mean the destruction of Jerusalem, or the end of the Jewish economy. And the meaning has been supposed to be, he who perseveres in bearing these persecutions to the end of the wars will be safe.

God will protect his people from harm, so that not a hair of the head will perish. Others, with more probability, have referred this to final salvation, and refer the "end" to the close of life. He who bears afflictions and persecutions faithfully—who constantly adheres to his religion, and does not shrink until death—will be saved, or will enter heaven.

So Luke 21:18 says, there should not a hair of the head perish; i.e., they will be saved. A hair of the head, or the smallest part or portion, is a proverbial expression, denoting the certainty and completeness of their salvation. Luke 21:19 further adds, In your patience possess ye your souls. That is, keep your souls patient; keep proper possession of patience as your own. It is a part of religion to teach it; and in these trying times let it not depart from you.