Exodus 15:10

Thou didst blow with the wind from before Thee, O Lord, and the waves of the sea covered them; they went down, and sank as lead in the proud waters.

NASHAPHTA’ WITH THY WIND. Rabbi Abraham ibn Ezra said that nashaphta is derived from the root nesheph (twilight), (twilight): the nesheph after sundown, and the nesheph before sunrise” (Ibn Ezra)! Here the nesheph before sunrise is referred to. for it was at twilight that He brought the wind which caused the water to return and drown the pursuers. Rashi explained it “as an expression for ‘blowing,’ similar in usage to the verse, When ‘nashaph’ (He bloweth) upon them, they wither.” Rashi has explained it well.
My opinion, furthermore, is that the purport of nashaphta, [written with the letter phei], is like [that written] with a beth: Thou ‘nashavta’ (didst blow) with Thy wind. The usage of the word is similar to: Because the breath of the Eternal ‘nashva’ (bloweth) upon it;, Verse 7. ‘yasheiv’ (He bloweth) His wind, and the waters flow. These two letters — [the phei or pei and the beth] — are of similar usage, just as in the verses: ‘al gapei’ (Upon) the highest places of the city, which is like al gabei; ‘im b’gapo’ (if by himself), which is like im b’gabo. Similarly: And substance ‘yivzor’ (he shall scatter) among them; ‘bizar’ (He hath scattered) the peoples. These are expressions of pizur (scattering), [with the letter beth serving here as phei] and the kuph. In proper names, these letters also interchange, e.g., Shovach, and Shophach. And our Rabbis say in the Mishnah: “[If produce is proclaimed] hevkeir (ownerless) for the benefit of the poor [only], it is deemed hevkeir (ownerless).” for a phei, and therefore he quotes only the beginning of the Mishnah. [The word hevkeir] is like hephkeir (ownerless). From the expression, The grains ‘avshu’ (shrivel) comes the word ipush (musty). The term ben p’kua, [an animal taken alive out of the slaughtered mother’s womb], is used in place of ben b’kua, because the mother was “ripped open” and there was found in it a living offspring of nine months.
In my opinion also, ‘hichpishani’ in ashes is like ‘hichbishani’ (He presses me) [or “He made me cower”] in ashes, the usage of the word being similar to: And replenish the earth, ‘v’chivshuha’ (and subdue it); ‘yichbosh’ (He will subdue) our iniquities. In the language of the Rabbis we also find: “a measure which is k’phushah,” meaning k’vushah, [a measure into which the contents have been “compressed”, and which therefore contains more than its normal measure].
The purport of the verse is thus: “with Your strong and mighty wind, the waters of the sea were piled up, and when You blew the wind with which You control the sea, the sea covered them.” This is the intent of the verse, And the sea returned to its strength when the morning appeared, for He caused the wind to blow on it as He does at His strength when He ruleth the proud swelling of the sea.

צללו כעופרת במים, they sank quickly like lead although the waters were so turbulent [which usually delays the sinking even of objects of heavy specific weight such a lead. Ed.]

נשפת ברוחך, You used the very same wind You had used to dry out the sea bed after splitting it to now turn against the pursuers and to turned into overwhelming and turbulent waters.

אדירים, not a reference to the waters but to the men who had been considered mighty, invincible, etc. [I suppose the unusual exegesis is based on the dividing tone sign tipcha under the word במים, which indicates that it belongs to the preceding words. Ed.] The people to whom Moses refers are the ones who had been described in 14,7 as שלישים על כולו.