Sarah: Genesis 17:21, Genesis 18:10-14, Genesis 21:2-3, Genesis 21:6; 2 Kings 4:16-17; Luke 1:13-20; Romans 9:6-9; Galatians 4:28-31
Isaac: Yitzchak:, which we change into Isaac, signifies laughter; in allusion to Abraham's laughing, Genesis 17:17. By this Abraham did not express his unbelief or weakness of faith, but his joy at the prospect of the fulfilment of so glorious a promise; and to this our Lord evidently alludes, John 8:56.