Genesis 17:15 - Coke's Commentary on the Holy Bible

As for Sarai thy wife, &c.— God now proceeds to reveal to Abraham, that the son of the promise should descend from his wife Sarai, whose name also he changes from Sarai, which signifies, say interpreters, my lady, to Sarah, which signifies, according to some, lady, or princess, absolutely, i.e.. not of one family only; or, according to others, princess of multitudes, which seems the most probable interpretation, not only from the occasion, but on account of the addition of the same letter ה to her name, which was added to Abram's; and which, consequently, should import the same thing.