Genesis 15:7 And he said unto him, I am the Lord that brought thee out of Ur of the Chaldees, to give thee this land to inherit it. 8 And he said, Lord God, whereby shall I know that I shall inherit it? 9 And he said unto him, Take me an heifer of three years old, and a she goat of three years old, and a ram of three years old, and a turtledove, and a young pigeon.
[Patriarchs & Prophets pp 137>138] When Abraham had been nearly twenty-five years in Canaan, the Lord appeared unto him, and said, “I am the Almighty God; walk before Me, and be thou perfect.” In awe, the patriarch fell upon his face, and the message continued: “Behold, My covenant is with thee, and thou shalt be a father of many nations.” In token of the fulfillment of this covenant, his name, heretofore called Abram, was changed to Abraham, which signifies, “father of a great multitude.” Sarai's name became Sarah—“princess;” for, said the divine Voice, “she shall be a mother of nations; kings of people shall be of her.”
At this time the rite of circumcision was given to Abraham as “a seal of the righteousness of the faith which he had yet being uncircumcised.” Romans 4:11. It was to be observed by the patriarch and his descendants as a token that they were devoted to the service of God and thus separated from idolaters, and that God accepted them as His peculiar treasure. By this rite they were pledged to fulfill, on their part, the conditions of the covenant made with Abraham. They were not to contract marriages with the heathen; for by so doing they would lose their reverence for God and His holy law; they would be tempted to engage in the sinful practices of other nations, and would be seduced into idolatry.
God conferred great honor upon Abraham. Angels of heaven walked and talked with him as friend with friend. When judgments were about to be visited upon Sodom, the fact was not hidden from him, and he became an intercessor with God for sinners. His interview with the angels presents also a beautiful example of hospitality. In the hot summer noontide the patriarch was sitting in his tent door, looking out over the quiet landscape, when he saw in the distance three travelers approaching. Before reaching his tent, the strangers halted, as if consulting as to their course.
Without waiting for them to solicit favors, Abraham rose quickly, and as they were apparently turning in another direction, he hastened after them, and with the utmost courtesy urged them to honor him by tarrying for refreshment. With his own hands he brought water that they might wash the dust of travel from their feet. He himself selected their food, and while they were at rest under the cooling shade, an entertainment was made ready, and he stood respectfully beside them while they partook of his hospitality. This act of courtesy God regarded of sufficient importance to record in His word; and a thousand years later it was referred to by an inspired apostle.
Hebrews 13:2 “Be not forgetful to entertain strangers: for thereby some have entertained angels unawares.”