Reference for Berakhot 20:16

בשלמא למ"ד אכסדרה היינו דכתיב קיר אלא למ"ד עלייה מאי קיר

This is all very well according to him who says it was a verandah, since it is written kir "a wall" ; but for him who says it was an upper chamber, what means kir?

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