Summary: God reaffirms the promise and reveals His judgment, mercy, and fairness to Abraham.
Of all the people of the world, God has chosen a childless man named Abraham. This man will be the father of many nations and he’ll inherit a Promised Land; but years and years go by and nothing happens. Abraham still lives in a tent on someone else’s property and he has no son. He’d hoped to have a son through a different woman, but God rejected Ishmael and refused to establish His covenant with him. As a sign of the covenant, God commanded Abraham to be circumcised. This permanent alteration would forever remind Abraham to live by faith and not by the flesh. He has cut away the foreskin.
This is where we pick up our study, and I’d like to point out that everything between chapters 17-21:7 all happen in one year (17:1; 21:5).
And the LORD appeared unto him in the plains of Mamre:
You’ll remember that Mamre is an Amorite man and an ally (14:13). Abraham has pitched his tents on Mamre’s land,
and he sat in the tent door in the heat of the day; 2And he lift up his eyes and looked, and, lo, three men stood by him:
Now we know from later in the story that two of these men are angels (19:13); they’re the ones who go down and stay in Lot’s house before destroying Sodom. The other man is called “the LORD” (:13) which is a name reserved for God, and we know that Christ is God in the flesh. So: Christ and two of His angels come to visit Abraham.
and when he saw them, he ran to meet them from the tent door, and bowed himself toward the ground, 3And said, My LORD, if now I have found favour in thy sight, pass not away, I pray thee, from thy servant: 4Let a little water, I pray you, be fetched, and wash your feet, and rest yourselves under the tree: 5And I will fetch a morsel of bread, and comfort ye your hearts; after that ye shall pass on: for therefore are ye come to your servant.
It’s been debated whether he knew who these men were or not, but I think we can safely say that he at least knew something was different and special. When he sees them (he’s 100 years old), he runs to meet them, and he offers to take care of their needs (food, water, rest, and clean feet) before they go on their way.
And they said, So do, as thou hast said. 6And Abraham hastened into the tent unto Sarah, and said, Make ready quickly three measures of fine meal, knead it, and make cakes upon the hearth. 7And Abraham ran unto the herd, and fetched a calf tender and good, and gave it unto a young man; and he hasted to dress it. 8And 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.
Everything is done so quickly for these special guests, and then Abraham himself stands close by so he can serve them. The men eat the meal, and then they address the two reasons for their appearance:
9And they said unto him, Where is Sarah thy wife? And he said, Behold, in the tent. 10And he said, I will certainly return unto thee according to the time of life; and, lo, Sarah thy wife shall have a son.