1 Kings 18:30-32

30Then Elijah said to all the people, Draw near to me. And all the people drew near to him. And he repaired the altar of Jehovah which was broken down.

31And Elijah took twelve stones, according to the number of the tribes of the sons of Jacob, to whom the word of Jehovah came saying, Israel shall be thy name;

32and with the stones he built an altar in the name of Jehovah, and made a trench round about the altar, of the capacity of two measures of seed;