'Sky' in the Bible

David lifted up his eyes, and saw the angel of Yahweh standing between earth and the sky, having a drawn sword in his hand stretched out over Jerusalem. Then David and the elders, clothed in sackcloth, fell on their faces.

David built an altar to Yahweh there, and offered burnt offerings and peace offerings, and called on Yahweh; and he answered him from the sky by fire on the altar of burnt offering.

But David didn't take the number of them from twenty years old and under, because Yahweh had said he would increase Israel like the stars of the sky.