A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
job 40:1GOD'S SECOND ADDRESS. (Job 40:1-24)
the Lord--Hebrew, "JEHOVAH."
job 40:2he that contendeth--as Job had so often expressed a wish to do. Or, rebuketh. Does Job now still (after seeing and hearing of God's majesty and wisdom) wish to set God right?
answer it--namely, the questions I have asked.
job 40:4I am (too) vile (to reply). It is a very different thing to vindicate ourselves before God, from what it is before men. Job could do the latter, not the former.
lay . . . hand . . . upon . . . mouth--I have no plea to offer (Job 21:5; Jdg 18:19).
job 40:5Once . . . twice--oftentimes, more than once (Job 33:14, compare with Job 33:29; Psa 62:11):
I have spoken--namely, against God.
not answer--not plead against Thee.
job 40:6the Lord--JEHOVAH.
job 40:7(See on Job 38:3). Since Job has not only spoken against God, but accused Him of injustice, God challenges him to try, could he govern the world, as God by His power doth, and punish the proud and wicked (Job 40:7-14).
job 40:8Wilt thou not only contend with, but set aside My judgment or justice in the government of the world?
condemn--declare Me unrighteous, in order that thou mayest be accounted righteous (innocent; undeservingly afflicted).
job 40:9arm--God's omnipotence (Isa 53:1).
thunder--God's voice (Job 37:4).
job 40:10See, hast thou power and majesty like God's, to enable thee to judge and govern the world?
job 40:11rage--rather, pour out the redundant floods of, &c.
behold--Try, canst thou, as God, by a mere glance abase the proud (Isa 2:12, &c.)?
job 40:12proud--high (Dan 4:37).
in their place--on the spot; suddenly, before they can move from their place. (See on Job 34:26; Job 36:20).
job 40:13(Isa 2:10). Abase and remove them out of the sight of men.
bind . . . faces--that is, shut up their persons [MAURER]. But it refers rather to the custom of binding a cloth over the faces of persons about to be executed (Job 9:24; Est 7:8).
in secret--consign them to darkness.
job 40:14confess--rather, "extol"; "I also," who now censure thee. But since thou canst not do these works, thou must, instead of censuring, extol My government.
thine own . . . hand . . . save-- (Psa 44:3). So as to eternal salvation by Jesus Christ (Isa 59:16; Isa 63:5).
job 40:15God shows that if Job cannot bring under control the lower animals (of which he selects the two most striking, behemoth on land, leviathan in the water), much less is he capable of governing the world.
behemoth--The description in part agrees with the hippopotamus, in part with the elephant, but exactly in all details with neither. It is rather a poetical personification of the great Pachydermata, or Herbivora (so "he eateth grass"), the idea of the hippopotamus being predominant. In Job 40:17, "the tail like a cedar," hardly applies to the latter (so also Job 40:20, Job 40:23, "Jordan," a river which elephants alone could reach, but see on Job 40:23). On the other hand, Job 40:21-22 are characteristic of the amphibious river horse. So leviathan (the twisting animal), Job 41:1, is a generalized term for cetacea, pythons, saurians of the neighboring seas and rivers, including the crocodile, which is the most prominent, and is often associated with the river horse by old writers. "Behemoth" seems to be the Egyptian Pehemout, "water-ox," Hebraized, so-called as being like an ox, whence the Italian bombarino.
with thee--as I made thyself. Yet how great the difference! The manifold wisdom and power of God!
he eateth grass--marvellous in an animal living so much in the water; also strange, that such a monster should not be carnivorous.
job 40:16navel--rather, "muscles" of his belly; the weakest point of the elephant, therefore it is not meant.
job 40:17like a cedar--As the tempest bends the cedar, so it can move its smooth thick tail [UMBREIT]. But the cedar implies straightness and length, such as do not apply to the river horse's short tail, but perhaps to an extinct species of animal (see on Job 40:15).
wrapped--firmly twisted together, like a thick rope.
job 40:18strong--rather, "tubes" of copper [UMBREIT].
job 40:19Chief of the works of God; so "ways" (Job 26:14; Pro 8:22).
can make his sword to approach--rather, "has furnished him with his sword" (harpe), namely, the sickle-like teeth with which he cuts down grain. English Version, however, is literally right.
job 40:20The mountain is not his usual haunt. BOCHART says it is sometimes found there (?).
beasts . . . play--a graphic trait: though armed with such teeth, he lets the beasts play near him unhurt, for his food is grass.
job 40:21lieth--He leads an inactive life.
shady trees--rather, "lotus bushes"; as Job 40:22 requires.
job 40:22shady trees--Translate: "lotus bushes."
job 40:23Rather, "(Though) a river be violent (overflow), he trembleth not"; (for though living on land, he can live in the water, too); he is secure, though a Jordan swell up to his mouth. "Jordan" is used for any great river (consonant with the "behemoth"), being a poetical generalization (see on Job 40:15). The author cannot have been a Hebrew as UMBREIT asserts, or he would not adduce the Jordan, where there were no river horses. He alludes to it as a name for any river, but not as one known to him, except by hearsay.
job 40:24Rather, "Will any take him by open force" (literally, "before his eyes"), "or pierce his nose with cords?" No; he can only be taken by guile, and in a pitfall (Job 41:1-2).