36. The Jewish people are called rabbah, great, as it states (Shemos 4:22) ישראל בכורי בני, "My firstborn son, Yisrael." So, Yisrael is the firstborn, the greater and older son.
37. Chazal say, "Whoever answers Amen yehei shmei rabbah with all his might, his judgment is ripped up." Reb Yochanan says, "Even if one has the sin of avodah zorah, he will be forgiven" (Shabbos 119).
After one's passing, the court in heaven will ask him, לישועה צפית, "Did you wait for the salvation?" (Shabbos 31.). The Imrei Emes zt'l explains that he is asked לישועה צפית, did you wait and look forward to Hoshana Rabbah? We should look forward to this day because Hashem bestows salvation to Klal Yisrael on this day.
The Divrei Chaim of Sanz zt'l said that Hoshana Rabbah can be translated in three ways, and they are all correct. (a) רבא הושענא means "The great Hashem should save us." (b) רבה הושענא means Hashem should save the great Jewish nation. And (c) רבה הושענא means that Hashem should save us with a great salvation.
Rebbe Dovid Moshe of Tchortkov zt'l (whose yahrtzeit is on Hoshana Rabbah) said that Hoshana Rabba means we will be saved in the merit of saying "Amen yehei shmei rabbah".
Historical Example
During World War II, the Yidden of Yerushalayim made a kabbalah to improve how they say Amen yehei shmei rabbah. They began saying it with all their might and with kavanah. When the Nazi general, Rommel ym's, was in Mitzrayim, intending to bring his army to Eretz Yisrael, Rebbe Shlomke Zvhiler zt'l told his gabai, "I sense that the resha'im won't be able to conquer Eretz Yisrael because the Yidden improved how they recite Amen yehei shmei rabbah." And indeed, the Yidden of Eretz Yisrael were miraculously spared.
