1 Kings 18:32

And with the stones he built an altar in the name of the Lord: and he made a trench about the altar, as great as would contain two measures of seed.

Cross-reference

1 Kings 18:35 pours water on the altar built in verse 32, completing the setup for the fire test.

Exodus 20:24 commands altars where God records His name — Elijah builds an altar in the name of the Lord, following that principle.