And the LORD appeared unto him in the plains of Mamre: and he sat in the tent door in the heat of the day;

And the Lord appeared to him in the vale of Mambre as he was sitting at the door of his tent, in the very heat of the day.

And Jehovah appeareth unto him among the oaks of Mamre, and he is sitting at the opening of the tent, about the heat of the day;

Now the Lord came to him by the holy tree of Mamre, when he was seated in the doorway of his tent in the middle of the day;

And the LORD appeared unto him by the terebinths of Mamre, as he sat in the tent door in the heat of the day;

Deinde visus est illi Jehova in Querceto Mamre, quum ipse sederet in ostio tabernaculi, quando incalescebat dies.

And the Lord appeared unto him It is uncertain whether Moses says, that God afterwards appeared again unto Abraham; or whether, reverting to the previous history, he here introduces other circumstances, which he had not before mentioned. I prefer, however, the former of these interpretations; namely, that God confirmed the mind of his servant witha new vision; just as the faith of the saints requires, at intervals, renewed assistance. It is also possible that the promise was repeated for the sake of Sarah. What shall we say, if in this manner, he chose to do honor to the greatness of his grace? For the promise concerning Isaac, from whom, at length, redemption and salvation should shine forth to the world, cannot be extolled in terms adequate to its dignity. Whichever of these views be taken, we perceive that there was sufficient reason why Isaac was again promised. Concerning the word Mamre we have spoken in the thirteenth chapter Genesis 13:1. Probably a grove of oaks was in that place, and Abraham dwelt there, on account of the convenience of the situation.

And the Lord appeared - See note on Genesis 15:1.
Sat in the tent door - For the purpose of enjoying the refreshing air in the heat of the day, when the sun had most power. A custom still frequent among the Asiatics.

And the Lord appeared unto him in the plains of Mamre,.... That is, to Abraham; and very likely this appearance of God was quickly after the affair of the circumcision, to show his approbation of his ready obedience to his command; and at this time he was in the plains, or at the oaks of Mamre, the oaken grove there, as has been observed on Genesis 13:18; and which seems to be the best rendering of the words, since in Genesis 18:4; mention is made of a tree to sit and stand under; and Abraham might choose this place for his habitation, because of the shadiness of it, in those hot countries:
and he sat in the tent door, in the heat of the day; partly to cool and refresh himself, and partly to observe if any passengers passed by, to invite them in; this being a time of day when such needed refreshment, and it was proper for them to lie by a while, and not proceed on their journey until it was cooler: or rather to or "near" the tent door, as Noldius (g), or before it, without or under the shade of the tree, after mentioned.
(g) Ebr. Concord. Part. p. 13.

Abraham was waiting to entertain any weary traveller, for inns were not to be met with as among us. While Abraham was thus sitting, he saw three men coming. These were three heavenly beings in human bodies. Some think they were all created angels; others, that one of them was the Son of God, the Angel of the covenant. Washing the feet is customary in those hot climates, where only sandals are worn. We should not be forgetful to entertain strangers, for thereby some have entertained angels unawares, Hebrews 13:2; nay, the Lord of angels himself; as we always do, when for his sake we entertain the least of his brethren. Cheerful and obliging manners in showing kindness, are great ornaments to piety. Though our condescending Lord vouchsafes not personal visits to us, yet still by his Spirit he stands at the door and knocks; when we are inclined to open, he deigns to enter; and by his gracious consolations he provides a rich feast, of which we partake with him, Revelation 3:20.

ENTERTAINMENT OF ANGELS. (Genesis 18:1-8)
the Lord appeared--another manifestation of the divine presence, more familiar than any yet narrated; and more like that in the fulness of time, when the Word was made flesh.
plains of Mamre--rather, terebinth or oak of Mamre; a tall-spreading tree or grove of trees.
sat in the tent door--The tent itself being too close and sultry at noon, the shaded open front is usually resorted to for the air that may be stirring.

When sitting, about mid-day, in the grove of Mamre, in front of his tent, Abraham looked up and unexpectedly saw three men standing at some distance from him (עליו above him, looking down upon him as he sat), viz., Jehovah (Genesis 18:13) and two angels (Genesis 19:1); all three in human form. Perceiving at once that one of them was the Lord (אדני, i.e., God), he prostrated himself reverentially before them, and entreated them not to pass him by, but to suffer him to entertain them as his guests: "Let a little water be fetched, and wash your feet, and recline yourselves (השּׁען( sevle to recline, leaning upon the arm) under the tree." - "Comfort your hearts:" lit., "strengthen the heart," i.e., refresh yourselves by eating and drinking (Judges 19:5; 1-Kings 21:7). "For therefore (sc., to give me an opportunity to entertain you hospitably) have ye come over to your servant:" כּן על כּי does not stand for כּי כּן על (Ges. thes. p. 682), but means "because for this purpose" (vid., Ewald, 353).

This appearance of God to Abraham seems to have had in it more of freedom and familiarity, and less of grandeur and majesty, than those we have hitherto read of, and therefore more resembles that great visit which in the fulness of time the Son of God was to make to the world. He sat in the tent - door in the heat of the day - Not so much to repose himself, as to seek an opportunity of doing good, by giving entertainment to strangers.