The Torah first informs us of Sarah’s infertility at the end of parshas Noach (Bereishis 11.30). Textually, this precedes the biblical wedding announcement of Avraham and Sarah. We can almost sense trouble brewing. Fast forward five chapters to the end of Lech Lecha and more than ten years since Avraham’s relocation and we now sense Sarah’s frustration.
God promises that Avraham will be the patriarch of a great nation. Yet with Avraham in his eighties, there are no sons. In an act of desperation, Sarah encourages Avraham to take Hagar, her Egyptian slave so that Avraham can father a son. What can she hope to gain declaring that “perhaps I will be built up from her"? We can just imagine the surprise of both women when Hagar immediately conceives.
Hagar uncharacteristically assumes an air of superiority over Sarah because of her success in carrying Avraham’s progeny in contrast to Sarah’s failure. Sarah is indignant over the disrespect of her slave. Or maybe there is more egging her on. She turns on Avraham and seeks to lay the blame at his feet! Avraham shrugs it off and tells Sarah to do with Hagar as she wishes. So, Sarah torments Hagar until Hagar flees.
Recalling that Sarah is the primal Matriarch, we marvel at this behavior. First, how does a slave suddenly show contempt for her mistress? And how does the righteous Sarah come to treat Hagar so cruelly? How does infertility affect Avraham and Sarah? God promised Avraham an heir; Did God make this same promise to Sarah?