If a person has both a complete loaf of bread and a sliced
loaf of bread that he could use for the third meal on Shabbos, he should use
the whole loaf and save the sliced loaf for his melava malkah because
the third meal is more important than the melavah malkah. It is best if
a person can also begin his melavah malkah with a whole loaf of bread.
If a person mistakenly begins to cut his loaf before
reciting the blessing over bread, it is still considered a whole loaf with
respect to the mitzvah of lechem mishnah if he can lift the entire
loaf from the section which has been partly separated by the cut that he
If a small part of the loaf is missing, it may still be
considered a whole loaf for the mitzvah of lechem mishnah. Some
poskim hold that a medium sized loaf is considered whole until it is missing
a piece the size of an olive—the amount that can be missing from a small
loaf being proportionate to its size. Others hold that it can be missing one
forty-eighth of the loaf, the amount that is removed to fulfill the mitzvah
of chalah. In any case, if a little bit of the loaf is missing, but it still
looks whole, it can be used for lechem mishnah.
A matzah that has lost a small piece can be burned at the
edges to make it appear whole. Some are lenient and allow burning the edges
even of a matzah that has lost so much that it appears to have been broken
Rusks are slices of bread that have been re-baked. Each
re-baked slice is considered a whole loaf. A rusk that has lost a piece can
be treated like matzah, that is, if one burned the edges so that it appears
to have been baked as it is, it is considered a whole loaf for the mitzvah lechem mishnah.
If a person does not have a second loaf of bread, he can
borrow a loaf from a neighbor. Even though he cannot eat it and has to
return it, it can be used to fulfill the mitzvah of lechem mishnah.