However, Rashi seems to contradict himself. Rashi (in the end of DH Hakrev Osah)
writes that the reason the west side of the Mizbe'ach is considered "Lifnei Hashem"
is because the wall of the Ulam -- which separates the Mizbe'ach from the Heichal --
has a 20-Amah wide opening, which is the same width as the Chalal (open area) inside
the Heichal. Since the west side of the Mizbe'ach is opposite that opening, it is
considered "Lifnei Hashem."
From these words of Rashi it seems that "Lifnei Hashem" means that it is opposite the
Chalal, the inside, of the Heichal, and the thickness of the walls of the Heichal are
not included. Rashi also implies that if there would be a wall such as the wall of
the Ulam separating the Heichal from the Mizbe'ach, then it would *not* be called
"Lifnei Hashem!" This contradicts what he writes earlier (and later) that being
opposite the thickness of the walls of the Heichal *is* considered "Lifnei Hashem"
even though it is not opposite the opening of the Heichal and even though the wall of
the Ulam separates the Mizbe'ach from the inside of the Ulam! (RASHASH)
(a) The RASHASH suggests that if the verse would have said only "Lifnei Hashem"
without saying "El Pnei ha'Mizbe'ach," then we would have interpreted "Lifnei Hashem"
to mean opposite the actual opening of the Heichal and that the wall *is* considered
a separation between the opening of the Heichal and the Mizbe'ach. However, now that
the verse adds "El Pnei ha'Mizbe'ach," we are forced to modify our interpretation of
"Lifnei Hashem" to mean opposite *any* part of the Heichal, even opposite the walls
of the Heichal, even if the walls of the Ulam separate the Mizbe'ach from the
Heichal.
However, this does not fully answer the question. First, the words of Rashi which say
that the walls of the Ulam are not considered a separation because it has a 20-Amah
opening implies that we do take into account the width of the walls of the Heichal
when determining the location of "Lifnei Hashem." Also, it is not at all clear
according to the Rashash what was Rashi's source in asserting "Lifnei Hashem" would
have been interpreted in a different manner if not for the words "El Pnei
ha'Mizbe'ach." Why did Rashi have to introduce this new interpretation of "Lifnei
Hashem" which is not consistent with the conclusion of the Gemara?
(b) The most likely possibility is that the commentary of Rashi here(DH Hakrev)
contains a supplementary note (a "Hagahah") from the words "d'Ein Mafsik" until the
end of this comment. This "Hagahah" is expressing a different approach to the Sugya,
which does not conform to the rest of Rashi's explanation in the Sugya, but which
does conform to Rashi's explanation in Zevachim (63b) and in Menachos (19b).
In essence, there are two different approaches to understanding how the Beraisa
interprets the words "Lifnei Hashem." One approach is that "Lifnei Hashem" is
referring to the place where the Minchah is brought to the Mizbe'ach. That is Rashi's
approach in our Sugya, according to which the walls of the Heichal must be considered
"Lifnei Hashem" since the Minchah was brought to the corner of the Mizbe'ach which
was opposite the wall of the Heichal and not opposite the Heichal opening. Rashi (DH
Kulei) points out that according to this approach it is not clear how the Gemara
knows that Rebbi Elazar holds that the Mizbe'ach was entirely in the north; perhaps
it was just slightly further to the north than the Tana Kama holds (that is, perhaps
it was just slightly more to the north than the halfway mark).
In addition, the ROSH (cited by the Shitah Mekubetzes) asks that the Gemara in Yoma
(16b) quotes the view of Rebbi Elazar ben Yakov who maintains that the entire
Mizbe'ach was in the south. According to his opinion, *no* part of the southern face
of the Mizbe'ach was "Lifnei Hashem" -- opposite any of the Heichal, the opening of
the Heichal or its walls (the southern face, according to that opinion, was sixteen
Amos (southward) passed the opening of the Heichal). The Rosh is forced to say that
Rebbi Elazar Ben Yakov does not derive any requirement about where the Minchah must
be brought from the words "Lifnei Hashem."
Third, if opposite the the Heichal walls is also considered "Lifnei Hashem," then
even according to the Tana Kama the entire southern face should be considered "Lifnei
Hashem" (as long as the Minchah was placed more than an Amah above the ground). The
reason for this is because the Mishnah in Midos tells us that the Mizbe'ach measured
32 by 32 Amos only on the bottom-most Amah, but above that it receded an Amah on
every side. Accordingly, the southern face above one Amah would be opposite the
Heichal walls. (According to Rashi in our Sugya, the Minchah apparently must be
brought to the face of the Yesod of the Mizbe'ach since only the most southernly part
of the Mizbe'ach, protruding to the south, was considered "El Pnei ha'Mizbe'ach.)
In contrast, Rashi in Zevachim and Menachos takes a different approach. He explains
that "Lifnei Hashem" means opposite the door of the Heichal (even though Rashi here
refers to the Chalal, or open area, of the Heichal, which is 20 Amos, perhaps he
means that the entrance of the Heichal is somewhere in those 20 Amos, and wherever
that entrance is located is considered "Lifnei Hashem," but the rest of the Chalal is
not considered "Lifnei Hashem"). If only the area opposite the entrance of the
Heichal is considered "Lifnei Hashem," then why is the south-west corner considered
"Lifnei Hashem? It is opposite the *wall* of the Heichal and not opposite the
opening!
The answer is -- like the SHITAH MEKUBETZES in Zevachim (63:6) explains -- that
"Lifnei Hashem" is not referring to the place where the Minchah is placed; it does
not mean that the Minchah must be placed opposite the entrance of the Heichal.
Rather, it means that the Minchah must be placed on the *side of the Mizbe'ach* that
is opposite the face of the Heichal. Even though the Minchah may be placed further
down along that side (on part of the side which is not directly opposite the
Heichal), it is considered "Lifnei Hashem" since it is being placed on the same side
of the Mizbe'ach which is "Lifnei Hashem," which faces the entrance to the Heichal.
This also seems to be the intention of the Shitah Mekubetzes here (DH v'Higishu).
This answers the Rosh's question on the opinion of Rebbi Elazar ben Yakov. Even
according to Rebbi Elazar ben Yakov, the western side of the Mizbe'ach is considered
"Lifnei Hashem," since it is on the same side as the entrance to the Heichal.
This also answers why the Gemara says that according to Rebbi Elazar, the Mizbe'ach
was entirely in the north. It would not be enough to say that he holds that the
Mizbe'ach was merely moved slightly to the north. Rather, the southern wall of the
Mizbe'ach must not only be opposite the walls of the Heichal, but it must also be
opposite the entrance to the Heichal, which begins only five Amos from the center
point of the Azarah. "Kulah b'Tzafon" means that either all of the Mizbe'ach or
almost all of it (up to at least the last five Amos) was in the north.
This also answers why the southern side of the Mizbe'ach is not considered "Lifnei
Hashem" according to the Tana Kama, even that part of the southern side that is
higher up on the Mizbe'ach where it is opposite the wall of the Heichal.
This is the approach of Rashi in Zevachim and Menachos. The words at the end of Rashi
here (DH Hakrev) are following the approach of Rashi in Zevachim and Menachos, rather
than the approach of the rest of Rashi in this Sugya. This is why Rashi writes that
only what is opposite the opening of the Heichal is considered "Lifnei Hashem," but
where the wall of the Ulam separates the Heichal from the Mizbe'ach, it is not called
"Lifnei Hashem."