Question: As explained previously, if one has leftover bread, he should not remove it before bentching. Does this halachah only apply if there happen to be leftovers from the meal, or is there a reason to deliberately leave some bread over at the end of the meal?
Discussion: The Gemara22 teaches that anyone who does not leave bread on his table will never see a sign of blessing. Rashi23 explains that bread must be left over in case a beggar comes for a meal. Accordingly, one should leave over a respectable piece so the poor person can be adequately fed.24 Contemporary Poskim25 say that in locations where it is uncommon to share leftovers with poor people, this reason and application does not apply.
Another reason to ensure there are leftovers is to show the bounty of Hakodosh Boruch Hu; we not only have enough to satisfy our hunger but also have extra remaining after we are satiated.26 Additionally, the Zohar27 writes, “It is forbidden for a person to recite Birkas Hamazon at an empty table, as the Heavenly blessing does not rest on an empty space.” These reasons apply in all locations. However, leaving over a respectable piece is unnecessary, and even small pieces will suffice.28 Nevertheless, leaving over minuscule crumbs is not enough, as they have no significance.29
The above-mentioned Gemara asks that this requirement to leave bread on the table seems to contradict another ruling, which states that if one leaves bread on his table, it is as if he has served avodah zarah.30 The Gemara answers that specifically bringing out a whole loaf when there are pieces on the table is forbidden because it then appears as if he is bringing the loaf to honor the avodah zarah, given that there are already pieces of bread on the table.
Based on this answer, the following rules apply:
If there is no bread on the table, it is appropriate to bring out either a loaf or pieces of bread.31
If there are already pieces of bread on the table, bringing out a whole loaf is forbidden.32
If there is a whole loaf on the table, bringing out pieces of bread is forbidden.33
When pieces of bread and a whole loaf are on the table, some Poskim say that one should remove the pieces.34 Others say there is only an issue with bringing additional bread to the table; leaving what is already there is permitted.35 Certainly, on Shabbos, both the loaf and pieces may be left on the table for Birkas Hamazon.36
Some have a custom on Friday night of bringing or leaving a loaf of bread on the table after Birkas Hamazon to prepare the table for the daytime meal. This practice is done in honor of Shabbos and is therefore permitted.37 However, some argue that this also appears as if one is setting the table for avodah zarah and must be avoided.
22 Sanhedrin 92a.
23 ד"ה והא.
24 Sha’ar Hatziyun 180:3.
25 R’ Y. S. Elyashiv cited in Vezos Haberachah 15, p. 140 (5777 edition); Az Nidberu 11:46. See there that one should not leave over a large amount if it will be discarded.
26 Levush 180:2, cited in Mishnah Berurah 180:2.
27 Parashas Yisro 87b, cited in Aruch Hashulchan 180:2.
28 See footnote 25.
29 R’ Y. S. Elyashiv, cited in Eitz Hasadeh 35, footnote 25.
30 A common way of serving the avodah zarah, known as Gad, was to leave a table set with food and drinks (Rashi, ד"ה המשייר.
31 Mishnah Berurah 180:4; Vezos Haberachah 15, p. 140.
32 Shulchan Aruch 180:2 with Mishnah Berurah 4.
33 Mishnah Berurah 180:5.
34 Pri Megadim cited in Mishnah Berurah ibid.
35 Taz cited in Mishnah Berurah ibid.
36 Mishnah Berurah ibid.
37 Taz 180:1 and in Yoreh Deah 178:7