Daf Yomi - Rosh Hashana 3 - MENTIONING SHABBOS

Rabbi Elozar learns from a different source that kings are counted from the month of Nissan. It is written in Divrei Hayomim regarding Shlomo Hamelech “He began to build in the second month, in the second, in the fourth year of his sovereignty.” The words ‘in the second’ are extra. Why are those words repeated? Rabbi Elozar explains it to be referring to the second month from when the king’s reign is counted. It is evident that the second month of the year, Iyar is the second month of the king’s year, which starts in Nissan.

The Gemora explains that the extra words ‘in the second’ cannot be referring to the second day of the week since we do not find such a term written in the Torah.

Tosfos cites from a Yerushalmi that the verse in Breishis “There was evening, there was morning, a second day” is not referring to the day of the week but rather to the second day of Creation.

Sfas Emes asks from several verses in Parshas B’shalach that state that the manna fell on the sixth day. He answers that perhaps our Gemora was only referring to the second day but other days of the week are mentioned in the Torah.
The Ramban in Parshas Bo points out that other nations assign intrinsic names to the days of week (such as Sunday, Monday . . . or dimanche, lundi . . .) whereas we denominate every day relative to Shabbos (yom rishon, - “first day” - yom sheni - “second day . . B’Shabbos). This is a fulfillment of the mitzvah “Remember the Shabbos day to sanctify it.” This is similar to the custom of Shamai who would eat every day in honor of Shabbos. When he would find a better-quality animal, he would say that this should be set aside for Shabbos. This is why we mention every day in the ‘song of the day’ that today is the first day from Shabbos.

Rav Yeruchem Fishel Perlow in his classic commentary on Rabbeinu Sadya Gaon writes that it is apparent from our Gemora not like the Ramban since the Gemora states unequivocally that we do not find the term ‘second day of the week in the Torah.’ The Yerushalmi adds that this calculation is not found in the Torah. According to the Ramban that it’s a mitzvah to mention the days of the week in this manner, why don’t we find the names of the days mentioned in this manner in the Torah?

Rav Nosson Grossman in his sefer Poseach Shaar offers a novel approach to explain the Ramban and our Gemora. There is a mitzvah to count the days of the week relative to Shabbos providing that this will bring about sanctity for this Shabbos or the Shabbos in the future. One who relates that a certain incident occurred on the second day since Shabbos does not sanctify the Shabbos at all. The custom of Shamai to designate an animal for this Shabbos, stating in the ‘song of the day’ that today is the second day of the Shabbos and writing in a divorce contract the day relative to Shabbos are all sanctifying this Shabbos and one fulfills the mitzvah of “Remember the Shabbos day to sanctify it.”

I found the following discussion in the Hearos blog on the daf related to our issue.

Hearos/

When we refer to the day of the week as "rishon b'Shabbos, sheini b'Shabbos".... Does it mean: 1. Day one from Shabbos. 2. Day one to Shabbos 3. Day one of the week?
The Beis Shmuel (Even Haezer 126:7) says that in Gittin we should write "b'Shabbos" and not "l'Shabbos" because the language "l'Shabbos" implies from Shabbos including Shabbos. Therefore, "l'Shabbos" would imply Shabbos is day 1, Sunday is day 2, Monday is day 3 etc. But now that we say "b'Shabbos" the problem is solved. Although I can't prove it, it seems to me that "b'Shabbos" also implies that we are counting from Shabbos, just that the language "b'Shabbos" indicates that Shabbos is not included in the number so that "sheini b'Shabbos" would correctly refer to Monday. Just as "l'Shabbos" is clearly counting from Shabbos, so too "b'Shabbos" is counting from Shabbos without including Shabbos in the count.

It would seem to me that according to the Poseach Shaar, this would not be the case. There is no mitzvah to mention that today is the second day since Shabbos. That is ancient history. The point of mentioning Shabbos is to sanctify the present Shabbos or the future Shabbos. Therefore, the meaning of “rishon b’Shabbos” is today is the first day of the week leading up to the upcoming Shabbos.