There isn't a specific Bible verse mentioning a "flee to Petra" command, but the concept stems from interpretations of biblical prophecies, particularly
Matthew 24:16-22, which instructs the Jewish people in Judea to flee to the mountains during the Great Tribulation, and
Revelation 12:6,
14, which describes Israel (the "woman") fleeing to a place prepared by God in the wilderness for 1,260 days. Some theologians and Bible scholars believe this wilderness place refers to Petra, due to its historically hidden nature, mountainous terrain, and the symbolic meaning of its Hebrew name, Sela, which means "rock".
The names of many towns and cities in the land of israel have specific meanings which are used to describe its function in scripture.
Bozrah or Petra: The Refuge in Jordan
The word Petra means rock and the word Bozrah means sheepfold and/or fortress. It is located in the ancient region of Edom which is southeast of the Dead Sea ...