Charles Ellicott Commentary Genesis 17:15

"And God said unto Abraham, As for Sarai thy wife, thou shalt not call her name Sarai, but Sarah shall her name be." — Genesis 17:15 (ASV)

Sarai. —Probably princely, an adjective of the same form as shaddai, Genesis 17:1; while Sarah means princess. The change of name shows that she was admitted to the covenant .