And the LORD asked Abraham, “Why did Sarah laugh and say, ‘Can I really bear a child when I am old?’
13. And the Lord said . Because the majesty of God had now been manifested in the angels, Moses expressly mentions his Name. We have before declared, in what sense the name of God is transferred to the angel; it is not, therefore, now necessary to repeat it: except, as it is always important to remark, that the word of the Lord is so precious...
These heavenly guests (being sent to confirm the promise lately made to Abraham, that he should have a son by Sarah), while they are receiving Abraham's kind entertainment, they return his kindness. He receives angels, and has angels' rewards, a gracious message from heaven, Mat 10:41. I. Care is taken that Sarah should be within hearing.
Commenting on Genesis 18:9-15
And the Lord said unto Abraham,.... This discovers who the person was that had been conversing with Abraham, that he was a divine Person, as appears by his name "Jehovah", as well as by his knowledge of Sarah's behaviour; he did not turn himself to her, that it might be more manifest that it was not upon the sight of her he judged she laughed...