Genesis 19:3

8. From this arises the question as to angels, whether they have bodies adapted to their duties and their swift motions from place to place, or are only spirits? For if we say that they have bodies, we are met by the passage: “He maketh His angels spirits;” and if we say that they have not bodies, a still greater difficulty meets us in explaining how, if they are without bodily form, it is written that they appeared to the bodily senses of men, accepted offers of hospitality, permitted their feet to be washed, and used the meat and drink which was provided for them. For it seems to involve us in less difficulty, if we suppose that the angels are there called spirits in the same manner as men are called souls, e.g. …

22. Yet, again, it is objected that except they were known to be angels of God, Lot would not have bowed himself with his face to the ground. Why, then, is both hospitality and food offered to them, as though they wanted such human succor? But whatever may here lie hid, let us now pursue that which we have undertaken. Two appear; both are called angels; they are invited plurally; he speaks as with two plurally, until the departure from Sodom. And then Scripture goes on to say, “And it came to pass, when they had brought them forth abroad, that they said, Escape for thy life; look not behind thee, neither stay thou in all the plain; escape to the mountain, and there thou shalt be saved, lest thou be consumed. And Lot said unto them, Oh! not so, my lord: be hold now, thy servant hath found grace in thy sight,” etc. …

107. In all the duties of hospitality kindly feeling must be shown to all, but greater respect must be given to the upright. For “Whosoever receiveth a righteous man, in the name of a righteous man, shall receive a righteous man’s reward,” as the Lord has said. Such is the favour in which hospitality stands with God, that not even the draught of cold water shall fail of getting a reward. Thou seest that Abraham, in looking for guests, received God Himself to entertain. Thou seest that Lot received the angels. And how dost thou know that when thou receivest men, thou dost not receive Christ? Christ may be in the stranger that comes, for Christ is there in the person of the poor, as He Himself says: “I was in prison and thou camest to Me, I was naked and thou didst clothe Me.”.

It is impossible for us briefly to run through everything. For who could count up almost all the patriarchs and numberless saints, some of whom for the preservation of life, others out of desire for a blessing, others out of pity, others to conceal some secret, others out of zeal for God, others in searching for the truth, became, so to speak, patrons of lying? And as all cannot be enumerated, so all ought not to be altogether passed over. For piety forced the blessed Joseph to raise a false charge against his brethren even with an oath by the life of the king, saying: “Ye are spies: to see the nakedness of the land are ye come;” and below: “send,” says he, “one of you, and bring your brothers hither: but ye shall be kept here until your words are made manifest whether ye speak the truth or no: but if not, by the life of Pharaoh, ye are spies.” For if he had not out of pity alarmed them …