Matthew Henry Commentary Genesis 18:9-15

"And they said unto him, Where is Sarah thy wife? And he said, Behold, in the tent. And he said, I will certainly return unto thee when the season cometh round; and, lo, Sarah thy wife shall have a son. And Sarah heard in the tent door, which was behind him. Now Abraham and Sarah were old, [and] well stricken in age; it had ceased to be with Sarah after the manner of women. And Sarah laughed within herself, saying, After I am waxed old shall I have pleasure, my lord being old also? And Jehovah said unto Abraham, Wherefore did Sarah laugh, saying, Shall I of a surety bear a child, who am old? Is anything too hard for Jehovah? At the set time I will return unto thee, when the season cometh round, and Sarah shall have a son. Then Sarah denied, saying, I laughed not; for she was afraid. And he said, Nay; but thou didst laugh." — Genesis 18:9-15 (ASV)

"'Where is Sarah your wife?' was asked. Note the answer: 'In the tent.' She was close by, in her proper place, occupied with her household concerns. Nothing is gained by aimless wandering. Those who are in their proper place and following their duty are most likely to receive comfort from God and His promises (Luke 2:8). We are slow of heart to believe and need line upon line to the same effect.

The blessings others receive from common providence, believers receive from the Divine promise, which makes them very sweet and very sure. The spiritual seed of Abraham owe their life, joy, hope, and all, to the promise. Sarah thought this news was too good to be true; she laughed, and therefore could not yet bring herself to believe it.

Sarah laughed. We might not have thought there was a difference between Sarah's laughter and Abraham's (Genesis 17:17); but He who searches the heart saw that the one sprang from unbelief and the other from faith. She denied that she had laughed. One sin commonly leads to another, and it is unlikely we will strictly keep to the truth when we question the Divine truth.

But those whom the Lord loves, He will rebuke, convict, silence, and bring to repentance, even if they sin before Him.