Adam Clarke on Matthew 24:13

But he that shall endure - The persecutions that shall come - unto the end; to the destruction of the Jewish polity, without growing cold or apostatizing - shall be saved, shall be delivered in all imminent dangers, and have his soul at last brought to an eternal glory. It is very remarkable that not a single Christian perished in the destruction of Jerusalem, though there were many there when Cestius Gallus invested the city; and, had he persevered in the siege, he would soon have rendered himself master of it; but, when he unexpectedly and unaccountably raised the siege, the Christians took that opportunity to escape. See Eusebius, Hist. Eccles lib. iii. c. 5, and Mr. Reading's note there; and see the note here on Mat 24:20 (note).