Hebrews 11:11

It was by faith that even Sara got strength to conceive, bearing a son when she was past the age for it ??because she considered she could rely on Him who gave the promise.

Hebrews 10:23

let us hold the hope we avow without wavering (for we can rely on him who gave us the Promise);

Luke 1:36

Look, there is your kinswoman Elizabeth! Even she has conceived a son in her old age, and she who was called barren is now in her sixth month;

Romans 4:20-21

no unbelief made him waver about God's promise; his faith won strength as he gave glory to God

1 Peter 3:5-6

It was in this way long ago that the holy women who hoped in God adorned themselves. They were submissive to their husbands.

Treasury of Scripture Knowledge

Summary

Through faith also Sara herself received strength to conceive seed, and was delivered of a child when she was past age, because she judged him faithful who had promised.

Bible References

Sara

Luke 1:36
Look, there is your kinswoman Elizabeth! Even she has conceived a son in her old age, and she who was called barren is now in her sixth month;
1 Peter 3:5
It was in this way long ago that the holy women who hoped in God adorned themselves. They were submissive to their husbands.

Because

Hebrews 10:23
let us hold the hope we avow without wavering (for we can rely on him who gave us the Promise);
Romans 4:20
no unbelief made him waver about God's promise; his faith won strength as he gave glory to God