The Lord appeared to Abraham in the plains of Mamre, while he sat in the tent door in the heat of the day. (Some versions mention the great trees of Mamre: the oaks or the terebinth trees.)
Abraham lifted up his eyes and looked, and 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.
We will find out that these three men are two angels (Genesis 19:1) and God in the flesh (Genesis 18:13). Many Bible scholars agree that this event is a pre-incarnate appearance of Christ, who is God in the form of man.
Abraham: My Lord, if I have found favor in your sight, do not pass by from your servant. Let a little water be fetched, and wash your feet, and rest yourselves under the tree. I will fetch a morsel of bread, and comfort you your hearts. Afterwards you shall pass on: for therefore are you come to your servant.
The three men: Do as you have said.
Abraham hastened into the tent to Sarah.
Abraham: Make ready quickly three measures of fine meal, knead it, and make cakes upon the hearth.
Abraham ran to the herd, and fetched a calf tender and good, and gave it to a young man, who hasted to dress it. 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 while they ate.
The men: Where is Sarah your wife?
Abraham: In the tent.
One of the three: I will certainly return to you according to the time of life; and Sarah your
wife shall have a son.
Sarah heard it in the tent door, which was behind him.
Now Abraham and Sarah were old and well stricken in age; and it ceased to be with Sarah after the manner of women.
Sarah had gone through menopause. She was also barren. (Genesis 11:30)
Sarah laughed within herself, saying, After I am waxed old shall I have pleasure, my lord being old also?
The Lord (to Abraham) Why did Sarah laugh, saying, Shall I of a surety bear a child, which am old? Is any thing too hard for the Lord? At the time appointed I will return to you, according to the time of life, and Sarah shall have a son.
Sarah (afraid): I did not laughed.
The Lord: No; but you did laugh.
The men rose up and looked toward Sodom.
Abraham went with them to bring them on the way.
Many people say that Sarah lied. I don’t believe she lied. God said she laughed. She said, I did not laugh (speaking of laughing out loud). God said, You did laugh. God let Sarah know that he knows the heart. She doesn’t have to make the outward sign for him to know the inward heart.
God revealed himself to Sarah on a personal level. I think Sarah needed this conversation with God as a faith booster.
Why was this necessary?
Through faith Sarah herself received strength to conceive seed, and was delivered of a child when she was past age, because she judged him faithful who had promised. (Hebrews 11:11)
Because, through faith, Sarah conceived.