'Altar to the Lord' in the Bible

Then Gad [the prophet] came to David that day and said to him, “Go up, set up an altar to the Lord on the threshing floor of Araunah the Jebusite [where you saw the angel].”

Araunah said, “Why has my lord the king come to his servant?” And David said, “To buy the threshing floor from you, to build an altar to the Lord, so that the plague may be held back from the people.”

David built an altar to the Lord there, and offered burnt offerings and peace offerings. So the Lord was moved [to compassion] by [David’s] prayer for the land, and the plague was held back from Israel.