Job 40:17
His tail sways like a cedar; the sinews of his thighs are tightly knit.
BSB
ASV
He moveth his tail like a cedar: The sinews of his thighs are knit together.
KJV
He moveth his tail like a cedar: the sinews of his stones are wrapped together.
He moveth his tail like a cedar - Margin, “setteth up.” The Hebrew word (חפץ châphêts) means “to bend, to curve;” and hence, it commonly denotes “to be inclined, favorably disposed to desire or please.” The obvious meaning here is, that this animal had some remarkable power of “bending” or “curving” its tail, and that there was some resemblance in this to the motion of the cedar-tree when moved by the wind. In “what” this resemblance consisted, or how this was a proof of its power, it is not quite easy to determine.
Some understand it of the trunk of the elephant, for the word signifies any extreme part, and in that there is indeed a wonderful strength. So strong is the elephant in his back and loins, and the sinews of his thighs, that he will carry a large wooden tower, and a great number of fighting men in it.
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.
Rare words are the text's own signal of a deliberate thread: the fewer the occurrences, the more the places it appears belong together.