This sermon, found in the papers of Mabillon, was published by Edmond Martène and Ursin Durand, and issued in vol. IX of the Collection of Ancient Writers and Monuments, p. 133 and following. There exists a not dissimilar sermon in the appendix to the fifth volume of the works of St. Augustine, no. 5, whose beginning is this: I have often admonished your charity. As for the title, I have already recalled, in the homilies no. 99, that I gave the one which is likewise inscribed On Hospitality. Finally, why I think this sermon ought to be attributed to Maximus is established both by the character of the style and by the authority of the most ancient codex 90 of the library of Santa Croce in Jerusalem. It is ascribed to St. Ambrose in codex Vaticanus Reginensis 85, p. 44, in which it reads thus:
Here begins the sermon on hospitality delivered by Saint Ambrose. But how few there are who do not perceive that nothing is less to be attributed to Ambrose than this sermon, whose character of style is plainly far different! We read in the book of Genesis that Abraham, when three men came upon him, ran to meet them in haste, and, prostrate on his face, entreated them to turn aside to his tent, so that by the hospitality of the saints he might receive the recompense of a blessing. For he knew this to be the command of the Lord who says: He who receives a prophet in the name of a prophet shall receive a prophet's reward; and he who receives a just man in the name of a just man shall receive a just man's reward (Matt. 10), and the rest.
Abraham therefore hastened to receive the holy men for this reason: that by the fellowship of hospitality he might merit the fellowship of holiness, and that while he shared the service of human kindness he might receive the sharing of justification. For this is the law of hospitality: that whatever sort he is who is received, such he makes to be also him who receives; which John the Evangelist most clearly indicated concerning those who received the Son of God, saying: But as many as received him, to them he gave power to become sons of God (John 1). You see therefore how great is the grace of hospitality, that he too is made a son of God who receives the Son of God in the lodging of his heart.
If, then, he who receives the Son of God is made a son of God, how much more does he who receives a just man earn the grace of a just man. For this is, as I said, the kindness of hospitality: that a holy man, coming and by the partnership of hospitality, makes his host to be this which he himself is. And who would refuse on such a condition to receive a holy man into the human kindness of his tent, so that, sharing a dwelling with him, he might share his holiness; and though for a time he had perhaps been a sinner, by receiving a just man he too might be just, as the prophet David says: With the holy you shall be holy, and with the innocent man you shall be innocent (Psalm 17).
Therefore, brethren, if our father Abraham, knowing this grace of hospitality, ran in haste to meet the three men who came upon him, of whom one was the Lord, and, prostrate on his face, entreated that they would come under the roof of his tent, how much more ought we to run to meet the holy priests when they come, and receive them with all entreaty into our dwellings, so that, according to David, we may be holy toward holy guests. Let no one now fear because of the conscience of his sins, let no one despair of pardon:
whoever receives a bishop in hospitality is now made just, though a little before he committed crimes, though he had been guilty; while he receives an innocent man, he is reformed by innocent merits, as the prophet says: With the innocent man you shall be innocent. Therefore, brethren, since we are the sons of Abraham, let us do the works of Abraham. He went forth to meet the three holy men; let us too run to meet the many priests. He, since he was just, received the blessed ones in hospitality, so that being just he might become more just; we who are sinners, let us receive the bishops, so that, our sins being washed away, we may be able to be just. Let us receive the saints, I say, so that against the nature of sin they may be granted to us.
For to just Abraham, through hospitality, since he had no sins, a son Isaac was granted against nature, who was granted against nature to such a degree that both cold old age despaired that he could be born, and his mother Sarah laughed. Sarah laughed, it says, because she was receiving a son not by nature but by grace; and indeed a blessed offspring, whose birth joys, not pains, had preceded. She was right indeed to laugh who received it with God as the author. Such, then, is blessed hospitality, that it always leaves gladness to its guests. Sarah laughs because she was freed from barrenness; I rejoice because I lay aside my sins. She was freed from a defect of the body; I have been washed from my shameful deeds.
She gives thanks that through hospitality she received her son Isaac; I rejoice that I have obtained pardon together with justice. But someone will perhaps say: Among those men who came upon Abraham, the Lord too was coming, which is indeed true; for so Scripture relates. But I say that even now Christ comes to us in his priests. Let us therefore imitate, brethren, Abraham. But why do I say Abraham? Let us imitate God our Father; for God willed men of two different nations to dwell in the one lodging of heaven; why should not we, who are brethren, abide with one another in one lodging?
And though he chose rather to contain our difference within the same house of the world, why should not our holy unanimity be held in one dwelling of tabernacles? Here it ends.