As a monument of God's great kindness and gracious manifestation of himself to him, which might bring this mercy to his remembrance in his return, Genesis 31:13. This was an ancient practice among the patriarchs, Genesis 35:14; but afterwards, upon the growing abuse of it among the heathens, it was forbidden by God, Leviticus 26:1 Deuteronomy 7:5, Deuteronomy 12:3. The oil he brought with him either for food or medicine, or for the anointing of himself, as need required; and poured it upon the top of the stone, as a token of his consecration thereof to this use to be a memorial of God's favour to him. Oil was used in sacrifices, and in the consecration of persons and places, Exodus 30:25,26 Exodus 40:9.
Related Commentaries of Genesis 28:18
Genesis 28:18
18 And Jacob rose up early in the morning, and took the stone that he had put for his pillows, and set it up for a pillar, and poured oil upon the top of it.