If a person had already fulfilled his obligation of Kiddush on Shabbat, may he recite Kiddush again for those who have not yet heard Kiddush?
This often happens on Shabbat morning, when a man attends synagogue and then participates in the Sebet after the services, where he hears Kiddush and then eats. May he repeat Kiddush for his wife and children when he returns home, or is he ineligible to recite Kiddush on their behalf, since he has already fulfilled his Kiddush obligation?
A similar situation arises when a Rabbi or other distinguished figure attends several affairs on Shabbat morning. He might recite Kiddush at the Sebet after services, and then attend a luncheon where he is given the honor of reciting Kiddush. Can he repeat Kiddush and fulfill the obligation for those in attendance, who have yet to hear or recite Kiddush?
A fundamental rule in Halacha establishes that "Af Al Pi She’yasa Mosi" – even if a person has already fulfilled his obligation, he may repeat the recitation to fulfill the requirement for others. Hence, a person who has already recited Kiddush may repeat Kiddush for his family or for anybody else, and the others fulfill their obligation by listening to his recitation. This Halacha applies without restriction; a person can recite Kiddush many times on Shabbat morning in order for others to fulfill their obligation by listening to his recitation. Thus, if a Rabbi attends even four or five Sebets on Shabbat morning, he may be given the honor of reciting Kiddush at each function.
In such a case, if the one who makes Kiddush does not wish to drink the wine, he may recite Kiddush and give the cup to somebody else (an adult) to drink. Normally, one cannot recite a Beracha over food on behalf of somebody else. If, for example, somebody wishes to drink some wine, he cannot ask his friend – who is not drinking wine – to recite the Beracha on his behalf. When it comes to Berachot over food, only the person who eats or drinks may recite the Beracha. Seemingly, then, a person who recites Kiddush – which consists of the Beracha of "Boreh Peri Hagefen" over wine – should be required to drink the wine, rather than allow somebody else to drink the wine. However, the Beracha of "Boreh Peri Hagefen" in Kiddush has the status of a "Birkat Ha’misva" – the Beracha recited over a Misva, rather than simply a Beracha recited over food. When it comes to Birkat Ha’misva, one may, indeed, recite the Beracha on behalf of somebody else. Therefore, one who recites Kiddush is not required to personally drink the wine, and may instead give the wine to another adult to drink. This Halacha is explicitly codified in the Shulhan Aruch (Orah Haim 273:4; listen to audio recording for precise citation). I indeed recall that Hacham Baruch Ben Haim, Zecher Sadik Libracha, would recite Habdala on Mosa’eh Shabbat in the terrace room of Shaare Zion, and, preferring not to drink the wine, would give the cup of wine to somebody else to drink.
Incidentally, we should note that the Kiddush recited on Shabbat morning differs from the Friday night Kiddush in that it essentially consists of only the Beracha over the wine. Although we customarily recite some Pesukim (verses) relevant to Shabbat as part of the Shabbat morning Kiddush, these verses are not actually part of the Kiddush. Therefore, if somebody does not have a Siddur available on Shabbat morning when he recites Kiddush, and he does not remember the verses customarily recited, he may simply recite the Beracha of "Boreh Peri Hagefen," and this suffices for the Shabbat morning Kiddush. Similarly, if a woman wishes to recite Kiddush so she can eat before her husband returns home from the synagogue on Shabbat morning, but she is not familiar with the customary text, she may simply recite the Beracha of "Boreh Peri Hagefen."
Summary: A person may recite Kiddush on behalf of others on Shabbat even if he had already recited or heard Kiddush. When a person recites Kiddush (or Habdala) on behalf of others, he does not have to drink the wine himself; he can give the wine to another adult to drink.
