'Hearth' in the Bible

"Command Aaron and his sons, 'This is the law of the burnt offering. The burnt offering is to remain on the hearth on the altar all night until morning, and the fire of the altar must be kept burning on it.

I will threaten Ariel, and she will mourn intensely and become like an altar hearth before me.

and the altar hearth, 7 feet, and from the altar hearth four horns projecting upward.

Now the altar hearth is a perfect square, 21 feet long and 21 feet wide.