Hebrews 11:11

Because she judged him faithful who had promised.— It may seem a difficulty, that the apostle should here tell us that Sarah judged him faithful who had promised, whereas in the history she seems not to have credited what was promised. But the answer is, Supposing that she did not at first believe the possibility or probabilityof her having a child at that time of life, yet if she afterwards believed, as there is no doubt but she did, upon the more full declaration of Jehovah, it fully answers the design of the apostle.