The Faith of Sarah

Genesis 23:1
And Sarah was an hundred and seven and twenty years old: these were the years of the life of Sarah.

Hebrews 11:11
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.

Although Abraham is called G-d's friend, Sarah didn't rely on her spouse's faith. Sarah had faith in G-d and in that faith was blessed with strength to do what was naturally impossible.