Isaiah 51:1-2

"Listen to Me, you who follow after righteousness, You who seek the LORD:
Look to the rock from which you were hewn, And to the hole of the pit from which you were dug. Look to Abraham your father, And to Sarah* who bore you; For I called him alone, And blessed him and increased him."

If Abraham was the Father of Faith & the Father of Many - what did that make Sarah?