The Mishnah in Masechet Berachot (45a) states that three who have eaten a bread meal together must perform a “Zimun” before reciting Birkat Hamazon. “Zimun” is performed by one of the three reciting, “Nevarech She’Achalnu Mishelo” at which point the others answer, “Baruch She’Achalnu Mishelo Uvtuvo Chayinu.” The Meiri writes that the reason why three individuals who ate together must perform the Zimun is in order for them to arouse themselves to recite Birkat Hamazon with the proper concentration. Others say the reason is in order to speak Hashem’s praises and to publicly thank Him for the abundance he has bestowed us with. The Zohar adds an additional mystical reason for this as well. The Poskim disagree whether the order of Zimun is a Torah obligation or merely rabbinic.
Although the primary text of the Zimun is as we have written above, nevertheless, the Sephardic custom is that before reciting the actual Zimun, the leader exclaims, “Hav Lan Ve’Nivrich Le’Malka Ila’a Kadisha” and the others reply, “Shamayim.” This means that they are requesting Heavenly permission to proceed as well. (Maran zt”l would regularly explain that the meaning of the word “Shamayim” refers to a Hebrew acronym meaning that all must concentrate on the leader’s recitation.) The leader should then proceed to recite the text of the Zimun that we have written above.
Some have the custom that the leader recites only the words “Hav Lan Ve’Nivrich” without the words “Le’Malka Ila’a Kadisha.” (This was indeed the custom of Maran zt”l.)
The Ashkenazi custom is to begin the Zimun with the leader proclaiming, “Rabbotai Nevarech” at which point the others reply, “Yehi Shem Hashem Mevorach Me’ata Ve’ad Olam.”
The text we have quoted above applies to a Zimun of between three and nine men who have eaten together. However, if ten men are present, the name of Hashem is mentioned in the Zimun with the leader proclaiming, “Nevarech Elokeinu She’Achalnu Mishelo” and the others answering “Baruch Elokeinu She’Achalnu Mishelo Uvtuvo Chayinu.” Following this, Birkat Hamazon is recited immediately.
In the next Halacha we shall, G-d-willing, discuss the age one can join as part of the Zimun.