Commentary for Exodus 14:31

את היד הגדלה denotes THE GREAT power which the HAND of the Holy One, blessed be He, had exercised. There are many meanings that are appropriate to the expression יד, hand, but all of them really signify the actual hand, and he who is explaining it must adapt the language according to the meaning of the passage.

AND ISRAEL SAW THE GREAT HAND. “I.e., the great power which the hand of the Holy One, blessed be He, had exercised. There are many meanings that are appropriate for the word yad (hand), but all of them signify the actual hand, and the interpreter must adapt the meaning according to the theme of the subject discussed.” Thus the language of Rashi. But Onkelos did not explain the great hand as referring to power, for he translated: “the might of the great hand.” And Rabbi Abraham ibn Ezra commented that it means “the great blow.” And so it also says, Behold, the hand of the Eternal is upon the cattle,⁸⁵Above, 9:3. [which means that a great plague will overtake them]; The hand of G-d was very heavy there,⁸⁶I Samuel 5:11. [which means that a great calamity befell the Philistines].
By way of the Truth, [the mystic teachings of the Cabala], the verse is stating that the great hand, which is the attribute of justice that G-d exercised upon the Egyptians, became revealed to them, since it was there inflicting punishment upon the Egyptians. This is like the verse, And upon earth He made thee to see His great fire.⁸⁷Deuteronomy 4:36. This is the right hand which dashes in pieces the enemy,⁸⁸See further, 15:6. and it is the arm of the Eternal, concerning which Scripture says, Awake, awake, put on strength, O arm of the Eternal;⁸⁹Isaiah 51:9. Art thou not it that dried up the sea?⁹⁰Ibid., Verse 10.

היד הגדולה אשר עשה ה' במצרים; a reference to the מדוי מצרים in Deuteronomy 7,15 which described afflictions suffered by the Egyptians while at the Sea of Reeds.