Hebrews 11:11

11 And by faith even Sarah, who was past childbearing age, was enabled to bear children because shea considered him faithful who had made the promise.

Read Hebrews 11:11 Using Other Translations

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.
By faith Sarah herself received power to conceive, even when she was past the age, since she considered him faithful who had promised.
It was by faith that even Sarah was able to have a child, though she was barren and was too old. She believed that God would keep his promise.