In the selfsame day was Abraham circumcised, and Ishmael his son. And all the men of his house, born in the house, and bought with money of the stranger, were circumcised with him.
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 he lift up his eyes and looked, and, lo, three men stood by him: and when he saw them, he ran to meet them from the tent door, and bowed himself toward the ground, and said, My Lord, if now I have found favour in thy sight, pass not away, I pray thee, from thy servant: let a little water, I pray you, be fetched, and wash your feet, and rest yourselves under the tree: And I will fetch a morsel of bread, and comfort ye your hearts; after that ye shall pass on: for therefore are ye come to your servant. And they said, So do, as thou hast said.
And Abraham hastened into the tent unto Sarah, and said, Make ready quickly three measures of fine meal, knead it, and make cakes upon the hearth. And Abraham ran unto the herd, and fetched a calf tender and good, and gave it unto a young man; and he hasted to dress it. And he took butter, and milk, and the calf which he had dressed, and set it before them; and he stood by them under the tree, and they did eat.
—Genesis xvii, 26, 27; xviii 1-8.
Be not forgetful to entertain strangers: for thereby some have entertained angels unawares.
—Hebrews xiii, 2.