Does Hashem (Kevayachol) have two Right Hands?
Rashi #1: The Torah is merely hinting here that when Yisrael do the will of Hashem, then His left Hand (Midas ha'Din) turns into a Right Hand 1 (Midas Rachamim). Consequently, one Right Hand saves Yisrael whilst the other one crushes the enemy. 2
Rashi #2: The same Right Hand with which Hashem saved Yisrael, He crushed the Egyptians - a feat which no human being is able to emulate.
Rashi #3 and Rashbam: The Pasuk is saying that Hashem's Right Hand (which is mighty), that Right Hand crushes the enemy. 3
Ramban #1 (citing Ibn Ezra): "Your Right Hand, Hashem, who is mighty ("Ne'dari" - masculine) in strength, Your right Hand crushes ("Tir'atz" - feminine) the enemy". 4
Ramban #2: "Your Right Hand Hashem, is mighty in strength, to humiliate whoever is arrogant and haughty. 5
Seforno: The Torah is stressing here that it is Hashem's Right Hand that is powerful and not that of Par'oh's army and elite troops, who rely on the might of their arms.
Hadar Zekenim: When they transgress His will, His right hand turns into a left hand.
The (stronger) right Hand, destroys the enemy - implying that even Hashem's Midas Rachamim agrees that they need to be destroyed.
And it is the way of the Torah to repeat a key word or phrase in this way, as we find on numerous occasions. See for example Tehilim, 92:10, 94:3, 93:3 (Rashi and Rashbam). See Ramban's objection to this explanation.
Simultaneously describing Hashem's Right Hand in the masculine and in the feminine.
What is the significance of the extra 'Yud' in "Nedari"?
Rashi, Da'as Zekenim and Hadar Zekenim: It is common for the Torah to add a 'Yud' on to an adjective in this way. 1
See for example Eichah 1:1, Bereishis 31:39 (Rashi) and Tehilim, 123:1 (Da'as Zekenim).
How will we reconcile the words "Nedari be'Ko'ach" with the Pasuk in Iyov, 37: 23 "Shakai Lo Metzanuhu Safgi Ko'ach"?
