Luke 21:21

Then let them that are in Judea flee unto the mountains; and let them that are in the midst of her depart out; and let not them that are in the country enter therein. For these are days of vengeance, that all things which are written may be fulfilled.

Flee unto the mountains ... History records that no Christian lost his life in the incredible devastation that overtook Jerusalem, the certainty that they did escape being the only authentication of Jesus' prophecy that is necessary. Eusebius tells how:

The Christians fled to Pella, a town in Trans-Jordan to the south of the Sea of Galilee. Pella was one of the Greek towns of the Decapolis, and there the Christians remained free from the Roman warfare and Jewish persecution.[22]

All things that are written may be fulfilled ... The great chapter of Deuteronomy 28:15-68 is surely included in this. Almost no form of calamity which was visited upon the Jews during the Roman war was left unmentioned in this chapter; but many of the prophets were just as specific (see Leviticus 26:31-33; Deuteronomy 32:35; 1 Kings 9:6-9; Daniel 9:26; Micah 3:12; and Zechariah 11:6).

These are the days of vengeance ... At last, as Jesus said, "All of the righteous blood shed on earth, from the blood of Abel" to the very time Jesus spoke, was coming upon the doomed city. Their greatest sin of all was in rejecting God's Son; and the penalty of that last act of rebellion was summarily executed upon Israel in the total destruction of their city.