2 Kings 6:14-17
14 Therefore he sent horses and chariots and a great army there, and they came by night and surrounded the city. 15 And when the servant of the man of God arose early and went out, there was an army, surrounding the city with horses and chariots. And his servant said to him, "Alas, my master! What shall we do?"
16 So he answered, "Do not fear, for those who are with us are more than those who are with them." 17 And Elisha prayed, and said, "Lord, I pray, open his eyes that he may see." Then the Lord opened the eyes of the young man, and he saw. And behold, the mountain was full of horses and chariots of fire all around Elisha.
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One of my favorites.