by faith, Sarah...

Yes, Sarah.  Even women are listed in this great chapter on the faith of believers.  In Sarah's case, mentioned after Isaac and Jacob, her son and grandson,  in Heb 11.11 the writer states:

"Through faith also Sarah herself received strength to coneive seed, and was delivered of a child when she was past age, because she judged Him faithful who had promised."

This blogger feels compelled to examine Sarah a bit closer.
First, in (Gen 17.15) her name was changed from "Sarai to Sarah."  Sarai in the Hebrew means "princess."  Sarah in the Hebrew means, "noblewoman."  The impression is that with the name change comes spiritual maturity.  The same thing occurs, more or less, when a woman gets married and goes from "Miss" to "Mrs." The difference indicates she has moved into a position of moral maturity.
However, when examining the life of Sarah as seen in Genesis, one notes that even "mature" women believers "mess up."

1. (Gen 17.15) her name change
2. (Gen 17.17-21) Abraham's unbelief at God's promise.  This most likely also influenced Sarah's thoughts on the Promise.
3. (Gen 18.6, 9) Preparations of Heaven's visitors.  Sarah's part was to prepare refreshment for them.  Is the Lord pleased to visit me and when He does is it "refreshing" to Him or disappointing?
4. (Gen 18.10-12) Sarah's reception of God's Promise - she laughed! "Within herself."  One would never openly declare disbelief at the Lord's Promise(s) but would doubt in the heart out of which "are the issues of life." (Prov 4.23)
5. (Gen 18.15) Sarah's denial of her "internal" reaction.  Obviously, her outward behaviors indicated in some way that she did not believe God's Promise.  Not unlike folks who say they are saved but are not faithful to the House of God or the way they live and/or dress.  It's clear that what is on the inside will show up on the outside.
6. (Gen 21.2) Amazingly, however, His mercies are sure in fulfilling His promise(s) despite unbelief.
7. (Gen 21.6,7) It seems her "scoffing" laughter is now turned to "joyful" laughter.  So it is with the believer, over and over, when the Lord works in our lives again and again.

Though she endured jealousy as a major stumbling block, later on, (Gen 21.9, 12), it is evident that this major miracle of giving birth in her old age after years of barrenness, increased her faith.
There is no doubt the "trial of our faith is much more precious than gold." (1 Pet 1.7)
Dear reader, when you are tried beyond what is humanly possible, trust Him.  Believe Him.  For we know, "He is faithful who has promised."  (Heb 10.12)