God went up from Abraham This expression contains a profitable doctrine, namely, that Abraham certainly knew this vision to be from God; for the ascent here spoken implies as much. And it is necessary for the pious to be fully assured that what they hear proceeds from God, in order that they may not be carried hither and thither but may depend alone upon heaven. And whereas God now, when he has spoken to us, does not openly ascend to heaven before our eyes; this ought to diminish nothing from the certainty of our faith; because a full manifestation of Him has been made in Christ, with which it is right that we should be satisfied. Besides, although God does not daily ascend upwards in a visible form, yet, in this his majesty is not less resplendent, that he raises us upwards by transforming us into his own image. Further, he gives sufficient authority to his word, when he seals it upon our hearts by his spirit.

God went up from Abraham - Ascended evidently before him, so that he had the fullest proof that it was no human being, no earthly angel or messenger, that talked with him; and the promise of a son in the course of a single year, at this set time in the next year, Genesis 17:21, which had every human probability against it, was to be the sure token of the truth of all that had hitherto taken place, and the proof that all that was farther promised should be fulfilled in its due time. Was it not in nearly the same way in which the Lord went up from Abraham, that Jesus Christ ascended to heaven in the presence of his disciples? Luke 24:51.

And he left off talking; with him,.... After he had finished all he had to say to him at this time. It was great condescension in the divine Being to talk with a creature; it was wonderful grace and kindness to make such promises to him, as he did, and indulge him with answers of prayer and communion with him; but the highest enjoyments of God here are not lasting; uninterrupted communion with him is reserved for another world:
and God went up from Abraham; from the earth, where he had been with Abraham, and ascended above him up to heaven, in a visible, and very likely in an human form, in which he descended: the Targums of Onkelos and Jonathan paraphrase it, "the glory of the Lord", the glorious Shechinah, the Lord of life and glory.

When God had finished His address and ascended again, Abraham immediately fulfilled the covenant duty enjoined upon him, by circumcision himself on that very day, along with all the male members of his house. Because Ishmael was 13 years old when he was circumcised, the Arabs even now defer circumcision to a much later period than the Jews, generally till between the ages of 5 and 13, and frequently even till the 13th year.