Job 41:24

“His heart is as firm as a stone; yea, as hard as a piece of the nether [millstone].] Which must be understood not of the substance but of the qualities of it, being bold, courageous, undaunted, and unmerciful; which is true both of the whale and crocodile, and particularly of the crocodile: Aelianus f1560 relates of one sort of them that they are unmerciful, though elsewhere f1561, he represents them as fearful.”

“heart--"In large beasts which are less acute in feeling, there is great firmness of the heart, and slower motion" [BOCHART]. The nether millstone, on which the upper turns, is especially hard.”

“His heart is as firm as a stone - As hard; as solid. Bochart remarks that the word “heart” here is not to be regarded as denoting the “courage” of the animal, as it sometimes does, but the heart literally. The statement occurs in the description of the various parts of the animal, and the object is to show that there was special firmness or solidity in every one of his members. There is special firmness or strength needed in the “hearts” of all animals, to enable them to propel the blood through the arteries of the body; and in an animal of the size of the crocodile, it is easy to see that the heart must be made capable of exerting vast force. But there is no reason to suppose that the…”

“Nether mill - stone - Which being to bear the weight of the upper, ought to be the harder and stronger of the two. Job 41:25”

“as hard: Isa 48:4; Jer 5:3; Zac 7:12 Job 41:25”