Elijah challenged King Ahab and the prophets of Baal to prove that Baal was powerful by having Baal send fire from the sky to burn a calf on an altar.  Though the prophets of Baal danced and cut themselves, nothing happened.  Then Elijah built an altar and had it doused with water.  He prayed and asked God to prove His power in front of all of Israel.  God sent fire that consumed the offering and all the water.