Hollow with boards shalt thou make it,.... The frame of it being made of boards of shittim wood, there was nothing within side but the grate, which was put within the square, down into the middle of it, and so was light of carriage; though the Targum of Jonathan, and other Jewish writers, represent this hollow as filled up with dust and earth, to answer to the altar of earth Moses was before bid to make; but this seems quite contrary to the present direction: the hollowness of the altar may denote the emptiness of Christ when he became a sacrifice: he emptied himself, as it were, when he became incarnate, of all his greatness, glory, and riches, and became mean and poor for the sake of his people, that they through his poverty might be made rich, Php 2:7as it was showed thee in the mount, so shall they make it; or, "as he showed thee" , that is, God.
Moses had a model of this altar showed him, and he was to be careful to instruct the workmen, and see to it, that they built it exactly according to the model.