'Altar' in the Bible

Gad came that day to David, and said to him, "Go up, build an altar to Yahweh on the threshing floor of Araunah the Jebusite."

Araunah said, "Why has my lord the king come to his servant?" David said, "To buy your threshing floor, to build an altar to Yahweh, that the plague may be stopped from afflicting the people."

David built an altar to Yahweh there, and offered burnt offerings and peace offerings. So Yahweh was entreated for the land, and the plague was stayed from Israel.