Shir Ha-Ma'alot #21

The Guest’s Blessing

The Guest’s Blessing has its source in the Talmud (Berachot 46a) which says, "What does the guest bless? May it be the will of God that the host not be shamed in this world nor humiliated in the World-to-Come. And Rebbe (Rabbi Yehudah Ha-Nasi) would add the words: And may he be very successful with all his possessions, and may his possessions and our possessions be successful and close to the city. And may no evil impediment reign over his handiwork nor over our handiwork. And may there not appear, neither before him, nor before us, any thought of sin, transgression or iniquity, from this time and forever." Although the Shulchan Aruch rules that a guest should recite this (Orach Chaim 201:1), it is surprising that it is omitted in many siddurim and one fulfills his obligation with the shorter statement: "May the Merciful One bless our host and our hostess, themselves, their home, their children and all that is theirs." The long version, however, is in printed in Maran Ha-Rav Kook’s siddur, Olat Re’eiyah (vol. 1, pp. 368-369).
Expressing thanks to a host is a great element of ethics, as is explained at length by Rabbenu Bachya in the book "Hovot Levavot - Duties of the Heart" that expressing thanks is the central building block of all the worship of Hashem. This is the Alef-Bet - the ABC - of the ethics teachings.
"May it be the will of God that the host not be shamed in this world." Maran Ha-Rav Kook, explains: "That a guest who is eating not of his own, will necessarily not be saved from some measure of shame." "One who eats food which is not his is ashamed to look into the face of the one who gave it" (Jerusalem Talmud, Orlah 1:3 quoted in the Tosafot to Kiddushin 36b d.h. Mitzvah). Therefore, to counteract this, the guest blesses the host so that "his fee will be paid without a touch of shame and disgrace being mixed with it" (Olat Re’eiyah vol. 1, p. 368).