Hebrews 11:11

By [having] faith, Sarah herself received the ability to have children, even though she was [sterile, being] past the age of child-bearing, since she considered God faithful to His promise. [Note: Some translations consider "Abraham" to be the subject of this highly controversial verse. See Lightfoot, pages 222-225].

Hebrews 10:23

[So], we should hold on firmly to the profession of our hope [in God], without wavering from it, for God is faithful to His promises.

Luke 1:36

And consider this, your relative Elizabeth is also pregnant with a son in spite of her old age, and [even though] she was said to be unable to have children, she is now six months along.

Romans 4:20-21

Yet he looked for the promise of God [to be fulfilled] and did not waver, doubting [that it would happen], but his faith strengthened him. He honored God

1 Peter 3:5-6

For this is the way holy women in ancient times decorated themselves. Their hope was in God and they were known for being in subjection to their own 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
And consider this, your relative Elizabeth is also pregnant with a son in spite of her old age, and [even though] she was said to be unable to have children, she is now six months along.
1 Peter 3:5
For this is the way holy women in ancient times decorated themselves. Their hope was in God and they were known for being in subjection to their own husbands.

Because

Hebrews 10:23
[So], we should hold on firmly to the profession of our hope [in God], without wavering from it, for God is faithful to His promises.
Romans 4:20
Yet he looked for the promise of God [to be fulfilled] and did not waver, doubting [that it would happen], but his faith strengthened him. He honored God