If one eats some cake at a kiddush in shul and then goes home and eats the Shabbos meal and forgets retzei during birkas hamazon; should he repeat the bentching or do we say the Shabbos meal at home is like the third meal and since some rishonim hold one doesn’t need bread the halacha would be different?
Answer:
After eating mezonos at a kiddush, one must still repeat birkas hamazon after forgetting retzei at the second meal.
This is certainly true where the mezonos were not safek pas, meaning that they were sweet, filled with a filling, and crispy. If one of these conditions was missing, it is preferable to wash and eat some bread again, before repeating birkas hamazon.
Sources:
This interesting question has been discussed at some length by a number of authorities.
A number of sources indicate that one can only fulfill the mitzvah of the Shabbos meals with bread. See Tosafos, Pesachim 101a; Rosh, Arvei Pesachim siman 5; Talmidei Rabbeinu Yonah, Berachos 36b; Rambam, Shabbos Chap. 30, no. 9; Ritva, Shabbos 117b; among others.
This halachah emerges from the ruling of the Gemara (Berachos 49b), which states that one does not have to repeat birkas hamazon after omitting the extra insert of Rosh Chodesh, because there is no obligation to eat — unlike Shabbos and Yom Tov. It is prohibited to fast on Rosh Chodesh, and the Gemara must therefore be referring to an obligation to eat bread.
See also Shibolei Ha-Leket (93), as cited in the Beis Yosef (291), who implies that one can fulfill the mitvzah of the Shabbos meals with peiros, but the Beis Yosef understood that he refers to the third meal alone. See also Shaar Hamelech, Sukkah 6:7, and see Maggid Mishnah, on the above Rambam.
Based on this principle, it follows that mezonos do not fulfill the mitzvah of the second meal. The second meal (with bread) remains obligatory, and one must therefore repeat birkas hamazon if one forgets retzei. This is the ruling given by Zechor Le-Yitzchak (80), and also by Rav Shlomo Zalman Auerbach (Shemiras Shabbos Kehilchasah Vol. 2, p. 215).
Note that some dispute this (Divrei David 86; see Kaf Hachaim 188:40), however, Shut Divrei Shalom (3:51) explains that this opinion, which states that one does not have to repeat birkas hamazon under such circumstances, applies only when the second meal is eaten after chatzos.
Another point that must be raised is the issue of safek pas. Although some forms of mezonos are certainly not pas (bread), most forms of pastry/cake are safek pas, because they do not fulfill the three conditions (which are three opinions) of what constitutes pas haba be-kisnin. Some authorities therefore write that one who eats safek pas has perhaps fulfilled the seudah, and should not recite birkas hamazon again if retzei is forgotten. This point is raised by the Kehilas Yaakov (Steipler, Berachos 16), and by some of the sources mentioned above.
For this reason it is recommended for somebody who has eaten safek pas, and forgot retzei in the forthcoming meal, to eat bread again, thereby ensuring that one is obligated in birkas hamazon.
However, it is possible that even in this case, there is no doubt that people who know that they will be eating a meal soon, do not intend to fulfill the mitzvah of the second meal with their eating cake after kiddush.
There is room to investigate whether intention can play a part in this question. It can be argued that after having eaten, the obligation of the second meal is fulfilled irrespective of intention. Yet, it can also be argued that without intention, or with negative intention (which can be ascribed to somebody who is planning to eat a meal in half-an-hour), the mitzvah is not fulfilled, as we find with matzah (475:4), and even with regard to immersion in a mikva (see Chikrei Lev, Vol. 3, Yoreh De’ah 31).
Based on this argument, there is room to argue that in all cases of making kiddush before the meal, one would still repeat birkas hamazon after omitting retzei in the second meal. Yet, because there remains some doubt, and some opinions who write that one should not repeat birkas hamazon, it is preferable to eat more bread (after making hamotzi again), and then to recite birkas hamazon.
