Gen 12:7

“Please note that the same Moses says in another passage that God appeared to Abraham. Yet the same Moses hears from God that no man can see God and live. If God cannot be seen, how did God appear? If he appeared, how is it that he cannot be seen? For John says similarly, "No one has ever seen God." And the apostle Paul says, "Whom no man has seen or can see." But certainly Scripture does not lie; therefore God was really seen. Accordingly this can only mean that it was not the Father, who never has been seen, that was seen, but the Son, who willed to descend and to be seen, for the simple reason that he has descended. In fact, he is the "image of the invisible God," that our limited human nature and frailty might in time grow accustomed to see God the Father in him who is the Image of God, that is, in the Son of God. Gradually and by degrees, human frailty had to be strengthened by means of the Image for the glory of being able one day to see God the Father.”

“The sense of the expression, And there he built an altar unto the Eternal, who appeared unto him, is that he gave praise to the Glorious Name and offered unto Him a sacrifice of thanksgiving for His having appeared to him. Until now G-d had not appeared to him neither in a mar’eh nor in a machzeh. and Machzeh are terms for different degrees of prophetic vision. See Ramban further, 15:1. See also Moreh Nebuchim, II, 41-5, for full discussion of these terms and other prophetic experiences. Rather, the command, Get thee out of thy country, was said to him in a nocturnal dream or through Ruach Hakodesh., Chapter 45, beginning: “second degree of prophecy.” It is possible that the expression, Who appeared unto him, alludes to the mystery of the sacrifice. The one enlightened [in the mysteries of the Torah] will understand.”