Was struck today by Sarah's resemblance to the church in Genesis 21.9-12:
"And Sarah saw the son of Hagar the Egyptian, which she had born unto Abraham, mocking. Wherefore she said unto Abraham, Cast out this bondwoman and her son: for the son of this bondwoman shall not be heir with my son, even with Isaac. And the thing was very grievous in Abraham's sight because of his son. And God said unto Abraham, Let it not be grievous in thy sight because of the lad, and because of thy bondwoman; in all that Sarah hath said unto thee, hearken unto her voice; for in Isaac shall thy seed be called."
The church points us to Christ; we know Christ because the church tells us about Him. So even faithful Abraham -- the prototype of the faithful believer -- is commanded to listen to Sarah's voice.
The church is our mother (Galatians 4.26), and our mother shows us who our Father is.