Genesis 21:6

“And Sarah said, God hath made me to laugh, etc.] This she said on occasion of the name of her son Isaac, which name her husband had given him by divine direction, and to which she assented. This doubtless brought to her mind her former laughing, when she first heard that she should have a son, which was in a way of diffidence and distrust; but now God having given her a son, laid a foundation for laughter of another kind, for real, solid, joy and thankfulness: [so that] all that hear will laugh with me; not laugh at her, and deride her, as Piscator interprets it; but congratulate her, and rejoice with her on this occasion, as on a like one the neighbours of Elisabeth did with her,…”

“21:6-7 Sarah was filled with joy and praise for this amazing event—only God could enable her to have a child. 21:6 Sarah’s wordplay on the name Isaac (Hebrew yitskhaq, “he laughs”) shows that the laughter of unbelief when the promise was given (18:12) had changed to the laughter of joy at its fulfillment. Isaac’s name could refer to the pleasure of God and of his parents at his birth. Sarah knew that everyone who heard about this would laugh with her and rejoice at the news.”