Sarah: Gen 17:21, Gen 18:10-14, Gen 21:2-3, Gen 21:6; 2Ki 4:16-17; Luk 1:13-20; Rom 9:6-9; Gal 4:28-31
Isaac: Yitzchak, which we change into Isaac, signifies laughter; in allusion to Abraham's laughing, Gen 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, Joh 8:56.