Avraham answered that despite the importance of welcoming guests, “the honor of a king’s daughter is within” (Tehillim 45:14). This is why Sarah, out of modesty, remained in the tent. According to Rashi the ministering angels’ question was rhetorical, since they knew where Sarah was. They intended to call attention to her modesty and thus endear her to her husband. Rashi adds a second explanation: that the angels asked for Sarah in order to send her the wine cup of blessing. Sarah had to partake of this cup, since it brings blessings down from above and permeates the household with holiness. Until this day, it is a mitzvah for the husband to ensure that the kos bracha (wine cup of blessing held during grace after meal) is sent to his wife.
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