'Mountains' in the Bible

Now I lifted up my eyes again and looked, and behold, four chariots were coming forth from between the two mountains; and the mountains were bronze mountains.

You will flee by the valley of My mountains, for the valley of the mountains will reach to Azel; yes, you will flee just as you fled before the earthquake in the days of Uzziah king of Judah. Then the Lord, my God, will come, and all the holy ones with Him!