Genesis 28:18

18.And Jacob rose up early. Moses relates that the holy father was not satisfied with merely giving thanks at the time, but would also transmit a memorial of his gratitude to posterity. Therefore he raised a monument, and gave a name to the place, which implied that he thought such a signal benefit of God worthy to be celebrated in all ages. For this reason, the Scripture not only commands the faithful to sing the praises of God among their brethren; but also enjoins them to train their children to religious duties, and to propagate the worship of God among their descendants.

And set it up for a pillar. Moses does not mean that the stone was made an idol, but that it should be a special memorial. God indeed uses this word מצבה (matsbah,) when he forbids statues to be erected to himself, (Leviticus 26:1,) because almost all statues were objects of veneration, as if they were likenesses of God. But the design of Jacob was different; namely, that he might leave a testimony of the vision which had appeared unto him, not that he might represent God by that symbol or figure. Therefore the stone was not there placed by him, for the purpose of depressing the minds of men into any gross superstition, but rather of raising them upward. He used oil as a sign of consecration, and not without reason; for as, in the world, everything is profane which is destitute of the Spirit of God, so there is no pure religion except that which the heavenly unction sanctifies. And to this point the solemn right of consecration, which God commanded in his law, tends, in order that the faithful may learn to bring in nothing of their own, lest they should pollute the temple and worship of God. And though, in the times of Jacob, no teaching had yet been committed to writing; it is, nevertheless, certain that he had been imbued with that principle of piety which God from the beginning had infused into the hearts of the devout: wherefore, it is not to be ascribed to superstition that he poured oil upon the stone; but he rather testified, as I have said, that no worship can be acceptable to God, or pure, without the sanctification of the Spirit. Other commentators argue, with more subtlety, that the stone was a symbol of Christ, on whom all the graces of the Spirit were poured out, that all might draw out of his fullness; but I do not know that any such thing entered the mind of Moses or of Jacob. I am satisfied with what I have before stated, that a stone was erected to be a witness or a memorial (so to speak) of a vision, the benefit of which reaches to all ages. It may be asked, Whence did the holy man obtain oil in the desert? They who answer that it had been brought from a neighboring city are, in my opinion, greatly deceived; for this place was then void of inhabitants, as I shall soon show. I therefore rather conjecture, that on account of the necessity of the times, seeing that suitable accommodations could not always be had, he had taken some portion of food for his journey along with him; and as we know that great use was made of oil in those parts, it is no wonder if he carried a flagon of oil with his bread.