Surrounded by the Aramean army, who said, "Those who are with us are more than those who are with them"?

Answer: Elisha

Elisha told his frightened servant not to be afraid; then the LORD opened the servant's eyes to see horses and chariots of fire.

“When the servant of the man of God got up and went out early in the morning, behold, an army with horses and chariots had surrounded the city. So he asked Elisha, “Oh, my master, what are we to do?” “Do not be afraid,” Elisha answered, “for those who are with us are more than those who are with them.””— 2 Kings 6:15-16 (BSB)