In his neck remaineth strength - That is, strength is "permanently residing" there. It is not assumed for the moment, but his neck is so constructed as to be the abode of strength. The word here rendered "remaineth" (ילין yālı̂yn), means properly to pass the night; then to abide or dwell; and there is a designed contrast here with what is said of "sorrow" in this verse. This description of strength residing in the neck, agrees well with the crocodile; see the figure of the animal on p. 255. It is not easy, however, to see how this is applicable to the whale, as Prof. Lee supposes. The whale is endowed, indeed, with great strength, as Prof. Lee has shown, but that strength is manifested mainly by the stroke of the tail.
And sorrow is turned into joy before him - Margin, "rejoiceth." The proper meaning of the word used here (תדוץ tādûts) is "to dance, to leap, to skip;" and the sense is, that "terror dances before him." It does not refer to the motion of the animal, as if he were brisk and rapid. but it is a poetic expression, as if terror played or pranced along wherever he came. Strength "resided" in his neck, but his approach made terror and alarm play before him wherever he went; that is, produced terror and dread. In his neck is permanent, calm strength; before him, everything trembles and is agitated. The beauty of the passage lies in this contrast between the strength and firmness which repose calmly in the neck of the animal, and the consternation which he everywhere produces, causing all to tremble as he approaches. Bochart has well illustrated this from the Classical writers.

In his neck remaineth strength - Literally, "strength has its dwelling in his neck." The neck is the seat of strength of most animals; but the head and shoulders must be here meant, as the crocodile has no neck, being shaped nearly like a lizard.
And sorrow is turned into joy before him - ולפניו תדוץ דאבה ulephanaiv taduts deabah; "And destruction exulteth before him." This is as fine an image as can well be conceived. It is in the true spirit of poetry, the legitimate offspring of the genie createur. Our translation is simply insignificant.

In his neck remaineth strength, and (h) sorrow is turned into joy before him.
(h) Nothing is painful or hard for him.

In his neck remaineth strength,.... This is thought to be an argument against the whale, which is said to have no neck: but whatever joins the head and body may be called the neck, though ever so small; and the shorter the neck is, the stronger it is. It is also said by some, that the crocodile has no neck also; but the philosopher (x) is express for it, that it has one and moves it: and Pliny (y) speaks of it as turning its head upwards, which it could not do without a neck;
and sorrow is turned into joy before him; or leaps and dances before him; it departs from him: he is not afraid of anything, though ever so threatening. Or sorrow and distress at the sight of him, in men and fishes, make them leap, and hasten to get out of the way of him and escape him.
(x) Aristot. Hist. Animal. l. 9. c. 6. & Part. Animal l. 4. c. 11. (y) Nat. Hist. l. 8. c. 25.

remaineth--abideth permanently. His chief strength is in the neck.
sorrow--anxiety or dismay personified.
is turned into joy--rather, "danceth," "exulteth"; wherever he goes, he spreads terror "before him."

22 Great strength resteth upon his neck,
And despair danceth hence before him.
23 The flanks of his flesh are thickly set,
Fitting tightly to him, immoveable.
24 His heart is firm like stone,
And firm like the nether millstone.
25 The mighty are afraid of his rising up;
From alarm they miss their aim.
Overpowering strength lodges on its neck, i.e., has its abiding place there, and before it despair, prop. melting away, dissolution (דּאבה from דּאב, Arab. ḏ'b = דּוּב Hiph., Arab. ḍ'b II, to bring into a loose condition, synon. חמס), dances hence, i.e., spring up and away (ידוּץ, Arab. jadisu, to run away), i.e., it spreads before it a despondency which produces terror, and deprives of strength. Even the pendulous fleshy parts (מפּלי), especially of its belly, hang close together, דבקוּ, i.e., they are not flabby, but fit to it, like a metal casting, without moving, for the skin is very thick and covered with thick scales; and because the digestive apparatus of the animal occupies but little space, and the scales of the back are continued towards the belly, the tender parts appear smaller, narrower, and closer together than in other animals. יצוּק here is not, as Job 27:2; Job 29:6, the fut. of צוּק, but the part. of יצק, as also Job 41:24: its heart is firm and obdurate, as though it were of cast brass, hard as stone, and in fact as the nether millstone (פלח from פלח, falacha, to split, crush in pieces), which, because it has to bear the weight and friction of the upper, must be particularly hard. It is not intended of actual stone-like hardness, but only of its indomitable spirit and great tenacity of life: the activity of its heart is not so easily disturbed, and even fatal wounds do not so quickly bring it to a stand. משּׂמו from שׂת = שׂאת = שׂאת), primary form שׂאתּ, is better understood in the active sense: afraid of its rising, than the passive: of its exaltedness. אילים (according to another reading אלים) is not, with Ew., to be derived from איל (Arab. ı̂jal), a ram; but אילים Exodus 15:15; Ezekiel 17:13 (comp. גּירים 2-Chronicles 2:16, נירי 2-Samuel 22:29), אלים Ezekiel 31:11; Ezekiel 32:21, and אוּלים Cheth. 2-Kings 24:15, are only alternating forms and modes of writing of the participial adject., derived from אוּל (איל) first of all in the primary form awil (as גּר = gawir). The signif. assigned to the verb אול: to be thick = fleshy, which is said then to go over into the signif. to be stupid and strong (Ges. Handwrterb.), rests upon a misconception: âla is said of fluids "to become thick," because they are condensed, since they go back, i.e., sink in or settle (Ges. correctly in Thes.: notio crassitiei a retrocendendo). The verb âla, ja'ûlu, unites in itself the significations to go backward, to be forward, and to rule; the last two: anteriorem and superiorem esse, probably belong together, and אל signifies, therefore, a possessor of power, who is before and over others. התחטּא, Job 41:25, has the signif., which does not otherwise occur, to miss the mark (from חטא, Arab. chaṭiya, to miss, opp. Arab. ṣâb, to hit the mark), viz., (which is most natural where אילים is the subject spoken of) since they had designed the slaughter and capture of the monster. שׁברים is intended subjectively, as תּבירא = פּחד Exodus 15:16, Targ. II, and also as the Arab. thubûr, employed more in reference to the mind, can be used of pain.

And sorrow - Sorrow is his companion and harbinger, which attends upon him wheresoever he goes. So anger and fear are said by the poets to accompany the God of war.