Ramban on Genesis
I BEING OLD. This is the explanation of Sarah’s words, after I am waxed old.98Verse 12 here. And G-d’s words [that Sarah had said, “I being old“], were true, but for the sake of peace He did not reveal what she also said, namely, My lord being old also,98Verse 12 here. for [if He were quoting Sarah], He should have said, “I and my lord are old,” as Sarah had laughed concerning both of them.