Genesis 18:15

Then Sarah denied, saying, I laughed not; for she was afraid. And he said, Nay; but thou didst laugh.

Ver. 15. I laughed not: for she was afraid.] And well she might; for as everybody hath its shadow, so hath every sin its fear. Her sin she saw was detected, and her conscience she felt was troubled; hence her fear.

Nay, but thou didst laugh.] A lie must be roundly reproved, and the truth asserted. She laughed but within herself, but as good she might have laughed out aloud; for God searcheth the heart. "I pray thee, O Lord, was not this my saying, when I was in my country? Jon 4:2 No, Jonah, it was not thy saying, it was only thy thinking: but that is all one before him who understandeth thy thoughts afar off". Psa 139:2