Genesis 18:13 Commentary: Rashi, Ramban, Rashbam & Or HaChaim

האף אמנם means SHALL I REALLY BEAR?

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.

'ויאמר ה, the angel, the senior of the three.