Matthew Henry Commentary Genesis 18:1-8

"And Jehovah appeared unto him by the oaks of Mamre, as he sat in the tent door in the heat of the day; and he lifted up his eyes and looked, and, lo, three men stood over against him: and when he saw them, he ran to meet them from the tent door, and bowed himself to the earth, and said, My lord, if now I have found favor in thy sight, pass not away, I pray thee, from thy servant: let now a little water be fetched, and wash your feet, and rest yourselves under the tree: and I will fetch a morsel of bread, and strengthen ye your heart; after that ye shall pass on: forasmuch as ye are come to your servant. And they said, So do, as thou hast said. And Abraham hastened into the tent unto Sarah, and said, Make ready quickly three measures of fine meal, knead it, and make cakes. And Abraham ran unto the herd, and fetched a calf tender and good, and gave it unto the servant; and he hasted to dress it. And he took butter, and milk, and the calf which he had dressed, and set it before them; and he stood by them under the tree, and they did eat." — Genesis 18:1-8 (ASV)

Abraham was waiting to entertain any weary traveler, because inns were not as commonly found then as they are for us. While Abraham was sitting there, he saw three men coming. These were three heavenly beings in human bodies. Some think they were all created angels; others believe that one of them was the Son of God, the Angel of the covenant.

Washing the feet is customary in those hot climates, where only sandals are worn. We should not be forgetful to entertain strangers, for by doing so some have entertained angels unawares (Hebrews 13:2); indeed, even the Lord of angels himself; as we always do, when for his sake we entertain the least of his brothers and sisters. Cheerful and gracious manners in showing kindness are great ornaments to piety.

Though our condescending Lord does not grant us personal visits, yet still by his Spirit he stands at the door and knocks; when we are inclined to open, he condescends to enter; and by his gracious consolations he provides a rich feast, of which we partake with him (Revelation 3:20).