Philo Judaeus De Abrahamo 132

[132] For when the wise man entreats those persons who are in the guise of three travellers to come and lodge in his house, he speaks to them not as three persons, but as one, and says, "My lord, if I have found favour with thee, do not thou pass by thy servant." ¹ For the expressions, "my lord," and "with thee," and "do not thou pass by," and others of the same kind, are all such as are naturally addressed to a single individual, but not to many. And when those persons, having been entertained in his house, address their entertainer in an affectionate manner, it is again one of them who promises that he by himself will be present, and will bestow on him the seed of a child of his own, speaking in the following words: "I will return again and visit thee again, according to the time of life, and Sarah thy wife shall have a son." ²