Job 40:16

“Lo now, his strength [is] in his loins, etc.] The strength of the elephant is well known, being able to carry a castle on its back, with a number of men therein; but what follows does not seem so well to agree with it; and his force [is] in the navel of his belly; since the belly of the elephant is very tender; by means of which the rhinoceros, its enemy, in its fight with it, has the advantage of it, by getting under its belly, and ripping it up with its horn f1459. In like manner Eleazar the Jew killed one of the elephants of Antiochus, by getting between its legs, and thrusting his sword into its navel f1460; which fell and killed him with the weight of it. On the other hand, the “river…”

“navel--rather, "muscles" of his belly; the weakest point of the elephant, therefore it is not meant.”

“Lo now, his strength is in his loins - The inspection of the figure of the hippopotamus will show the accuracy of this. The strength of the elephant is in the neck; of the lion in the paw; of the horse and ox in the shoulders; but the principal power of the river-horse is in the loins; compare Nahum 2:1. This passage is one that proves that the elephant cannot be referred to. And his force is in the navel of his belly - The word which is here rendered “navel” (שׁריר shârı̂yr) means properly “firm, hard, tough,” and in the plural form, which occurs here, means the “firm,” or “tough” parts of the belly. It is not used to denote the “navel” in any place in the Bible, and should not have been…”

“Strength - He hath strength answerable to his bulk, but this strength by God's wise and merciful providence is not an offensive strength, consisting in, or put forth by horns or claws, as it is in ravenous creatures, but only defensive and seated in his loins, as it is in other creatures. Job 40:17”