Genesis 18:13

“And the Lord said unto Abraham, etc.] 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, but from his own omniscience; and he chose rather to speak to her husband than to her, appearing as a stranger, and that he might reprove her: wherefore did Sarah laugh, saying, shall I of a surety bear a child, which am old? suggesting there was no reason for it, and signifying his displeasure and indignation at it.”

“- The Visit of the Lord to Abraham 2. השׂתחיה vayı̂śtachû “bow,” or bend the body in token of respect to God or man. The attitude varies from a slight inclination of the body to entire prostration with the forehead touching the ground. 6. סאה se'ah a “seah,” about an English peck, the third part of an ephah. The ephah contained ten omers. The omer held about five pints. This chapter describes Abraham’s fellowship with God. On the gracious assurance of the Redeemer and Vindicator, “Fear not, I am thy shield and thy exceeding great reward,” he ceased to fear, and believed. On the solemn announcement of the Conqueror of evil and the Quickener of the dead, “I am God Almighty; walk before me…”

“18:13-15 Sarah thought her disbelieving laughter was hidden, but God knows human hearts (see Ps 69:5; Prov 20:27; Mark 4:22; Luke 8:43-48; Heb 4:13), whether they stagger at the promises or step out in faith (see Heb 11:11-12).”