In the 18th chapter of Genesis, Abraham is met by three angels, the day after the institution of circumcision as an observance of the law of the covenant made with God. According to St. Ambrose of Milan, since Abraham was uncircumcised when he was called by God and on the day he passed away, this establishes him as the “Progenitor” of all believers and not explicitly the father of the Jews. With this, God appears to Abraham at the Oak of Mamre as three men, a premonition to the Trinity, and yet in the form of those with faces like us. Knowing this, Abraham falls before them calling them “O Lord,” signifying the unity of three persons in one, singular essence. Abraham quickly makes three loaves for the angels before they make their way towards Sodom and Gomorrah.
In Gen. 18:2, Origen makes the juxtaposition of how Abraham has three men stand “before him” whereas Lot only receives two men which sit “in the street.” Origen then claims that this is a fair and just dispensation for Abraham as the Progenitor. Abraham’s hospitality acts as a symbolic representation of his understanding of the dispensation and his pious obedience to God. In the 7th pericope, Abraham fashions a calf for the three men to eat. Once finished, the Lord asks where Sarah is to bestow upon her the news that upon their return, her son will be born. Sarah asks “Am I, who am old, to bear a child?,” and denies this as a true sign from God given to her specifically. Sarah’s laughter expresses her doubt in this sign because she was afraid, this doesn’t rid herself of the sin of cowardice however when explained by Ephrem of Syria.