QUESTION: The Gemara teaches that if a person, during his lifetime, does not bow down at the blessing of "Modim" in the Shemoneh Esreh, after seven years in the grave his spine turns into a snake (Nachash). (The Girsa of the Tur (OC 121) is "after seventy years," meaning after he passes away.) Why is this an appropriate punishment for one who does not bow during Modim?
ANSWER: TOSFOS (16b, DH v'Hu) explains the intent of the Gemara here based on the Gemara in Berachos (12a) which teaches that when a person bows at "Modim" he should "straighten himself like a snake" (and bring his head up first). Hence, one who does not bow during "Modim" is punished measure-for-measure, and his spine becomes a snake.
Why, though, is one required to bow like a stick, and to rise like a snake, during "Modim"?
The Acharonim explain that the point of "Modim" is to show one's humility before Hash-m, Who grants a person everything he needs for his daily life. The Gemara in Sotah (9b) teaches that Hash-m originally made the snake the king of the beasts, but the snake was not grateful and it became arrogant and wanted even more. Hash-m punished the snake, saying, "I originally created you to walk with an upright stature, but now that you did not humble yourself you will walk upon your stomach." The snake, therefore, is a symbol of the punishment that befalls a person who does not humble himself and does not recognize that everything he has is a gift from Hash-m. When a person bows down, he should bow like a stick, reminding himself that there is a Master in Heaven Whose word he must obey (for a king rules with his stick; see Sotah 40a and Shabbos 52b).
When a person rises after bowing, he must remember that even when standing erect he should not do so in an arrogant manner. The Gemara here teaches that if a person does not bow during Modim and thereby commits the sin of the Nachash by standing erect and not recognizing Hash-m's dominion, after he dies his spine that did not bend will turn into a Nachash. (See MAHARSHA, and MAHARAL in Chidushei Agados and Nesivos Olam, Nesiv ha'Avodah #10).
(b) The sin of the snake was the sin of Esav, who refused to recognize Hash-m's dominion and arrogantly wanted everything for himself (see Rashi to Bereishis 33:9). The Nachash is equated with Esav in Midrashim which associate both of them with Sama'el, the Satan, which causes people to act in denial of Hash-m's presence. (See Rashi to Sukah 29a and Sotah 10b; regarding the Nachash, see Zohar, Bereishis 35b.)
TARGUM ONKELUS (Bereishis 25:27) describes Esav as "Nachash Yarchan" (according to the Girsa of the Ba'alei ha'Tosfos in Pane'ach Raza). This might mean that Esav shared the trait of the Nachash with regard to his "Yerech," his thigh. The thigh is the place from which a person begins to bow. Just as the Nachash stood with an erect posture and did not humble itself, Esav, too, did not bow and humble himself to Hash-m. Yakov, who knew this, realized that the way to overcome Esav was by humbling himself and bowing down to Hash-m. That is why, when he met Esav upon his return from Lavan, he greeted his brother by bowing down seven times (see Bereishis 33:3).
Similarly, the Gemara in Kidushin (29b) relates that when Rav Acha bar Yakov was faced with a fearsome Nachash, he vanquished it by bowing down seven times in prayer to Hash-m (see Insights there).
(c) This comparison between Esav and the Nachash lends support to the assertion of the MAHARSHA (Bava Kama 3b) that the four Avos Nezikin correspond to the four exiles. The Maharsha writes that Mav'eh corresponds to Esav, or Galus Edom, according to both interpretations of Mav'eh: if Mav'eh is Adam, it alludes to Esav who is called "Edom." If Mav'eh is Shen, it alludes to Esav whose profession is the Cherev (the Maharsha apparently means that the damage of the sword is referred to as eating, as in Yeshayah 1:20). According to the Midrash that compares Esav to the Nachash, Mav'eh alludes to Esav because Esav's poison is that of the snake, which is expressed from its teeth (Bava Kama 23b). The Maharsha adds that the verse the Gemara brings to show that Mav'eh is Shen, "Eich Nechpesu Esav Niv'u Matzpunav" (Ovadyah 1:6), is a verse that describes Esav.
Rav Mordechai Aran in NIFLA'OS MI'TORASECHA (Erech Mav'eh) points out that the only place in the Torah in which the word "Mav'eh" appears as Roshei Teivos (the first letters of four consecutive words) is the verse (Bamidbar 10:9)," v'Chi Savo'u Milchamah B'Artzechem Al Ha'Tzar ha'Tzorer Eschem, va'Hare'osem ba'Chatzotzeros...." Remarkably, this is the same verse that the RAMBAN (Mitzvas Aseh #5) cites as the source in the Torah to pray to Hash-m during a time of trouble, corresponding to the verse of "... Im Tiv'ayun Be'ayu" (Yeshayah 21:12), which the Gemara cites as the source that Mav'eh means Adam who prays to Hash-m!
Rav Aran points out that this explains the appearance of Mav'eh in this verse, according to the opinion that Mav'eh is Shen. It is the Shen of Esav which is the Shen of the Nachash and the Satan. The Zohar (Vayakhel 196b) explains that this verse describes the war against Sama'el, who is defeated by the blowing of the Shofar, "va'Hare'osem b'Chatzotzeros," on Rosh Hashanah.