Learn the Gemara “דף מד.”אלא אמר רב זביד (middle of the Amud) until “אתמר ר’ יוחנן ור’ יהושע בן לוי” eleven lines from bottom of the Amud)
Continue learning the Gemara “דף מד. “אתמר ר’ יוחנן ור’ יהושע בן לוי ( until top of דף מד: “א”ר אמי
Note: The difference between יסוד and מנהג נביאים that Rashi gives.
The Gemara concludes כאן במקדש כאן בגבולין
See how Rashi explains this answer
According to Rashi the נביאים set up the taking of Aravos outside the Beis Hamikdash.
Was this for all seven days of Sukkos or just the last day – Hoshana Rabbah?
Major Question:
The Gemara on מד says that the taking of Aravos on Hoshana Rabbah is זכר למקדש.
But the gemara now says it was a either a יסוד and מנהג נביאים?
See רבינו חננאל (on side of the Gemara) for a different explanation than Rashi
Learn רמב״ם הלכות לולב פרק ז הלכה כא-כב and מגיד משנה
https://hebrewbooks.org/pdfpager.aspx?req=14278&st=&pgnum=287
Major Question:
The Rambam says the mitzvah of Aravah we take on Hoshana Rabbah is both זכר למקדש and מנהג נביאים.
How could it be both?
What compelled the Rambam to give this explanation?
The Rambam seems to offer an entirely new reason than the גמרא מד as to why the mitzvah of Aravah is only one day זכר למקדש?
Learn ערוך לנר for an explanation for the Rambam
https://hebrewbooks.org/pdfpager.aspx?req=14414&st=&pgnum=171
Can we offer a different explanation for the Rambam based on the conclusion of the Gemara of כאן במקדש כאן בגבולין?
According to אבא שאול the mitzvah of Aravah in the Beis Hamikdash is learnt from the words ערבי נחל
Learn תוספת דף לד. “ואחת who asks where in the pasuk is it indicated that it’s limited to Beis Hamikdash?
See תוספת ראש
And ערוך לנר