The answer
This is what St. Ephrem the Syrian says:"And he lifted 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, (Genesis 18:2).Although Abraham ran from the tent toward them as if toward strangers, he ran to receive those strangers with love. His love for strangers was thus proved by the haste with which he ran to meet those strangers. Therefore the Lord, who had just appeared to him at the door of the tent, now appeared to Abraham clearly in one of the three. Abraham then fell down and worshiped him, seeking from him in whom majesty dwells that he condescend to enter his house and bless his dwelling. 'If I have found favor in your sight, do not pass by your servant.' God did not oppose him, for he said, 'Do as you have said.' Then Abraham ran to Sarah [telling her] to make three measures of wheat, and then he ran to the herd to get a fatted calf." (Ephrem the Syrian)
This is what all the Church Fathers said:
In the Old Testament, we do not refer to the Lord Jesus Christ as the incarnated Son of God, and we do not call him Jesus Christ, but rather the Son of God. Thus, the Lord Jesus Christ never appeared in the Old Testament, meaning the INCARNATED Son of God never appeared, but rather the Hypostasis of the Son.
Answered by His Eminence Metropolitan Youssef (opens in a new tab)