Surely the mountains bring him forth food - That is, though he lies commonly among the reeds and fens, and is in the water a considerable portion of his time, yet he also wanders to the mountains, and finds his food there. But the point of the remark here does not seem to be, that the mountains brought forth food for him, but that he gathered it "while all the wild beasts played around him, or sported in his very presence." It was remarkable that an animal so large and mighty, and armed with such a set of teeth, should not be carnivorous, and that the wild beasts on the mountains should continue their sports without danger or alarm in his very presence. This fact could be accounted for partly because the "motions" of the hippopotamus were so very slow and clumsy that the wild beasts had nothing to fear from him, and could easily escape from him if he were disposed to attack them, and partly from the fact that he seems to have "preferred" vegetable food. The hippopotamus is seldom carnivorous, except when driven by extreme hunger, and in no respect is he formed to be a beast of prey. In regard to "the fact" that the hippopotamus is sometimes found in mountainous or elevated places, see Bochart.

The mountains bring him forth food - It cannot therefore be the hippopotamus, as he is seldom found far from the rivers where he has his chief residence.
Where all the beasts of the field play - He frequents those places where he can have most prey. He makes a mock of all the beasts of the field. They can neither resist his power, nor escape from his agility. All this answers to what we know of the mammoth, but not at all to the hippopotamus.

Surely the mountains bring him forth food,.... Grass, which grows on mountains, and is the food of the river horse as well as of the elephant; and therefore is furnished with teeth like a scythe to mow it down; and it is not a small quantity that will suffice it, mountains only can supply it; and marvellous it is that a creature bred in a river should come out of it to seek its food on mountains. There is a creature in the northern parts, as in Russia, Greenland, &c. which is called morss and sea morss, and by the description of it is much like the river horse, of the size of an ox, and having an head like one, with two large long teeth standing out of its upper jaw, and an hairy skin (a), said to be an inch thick, and so tough that no lance will enter it (b); it comes out of the sea, and by its teeth gets up to the tops of mountains, and having fed on grass rolls itself down again into the sea; and this it does by putting its hinder feet to its teeth, and so falls from the mountain with great celerity, as on a sledge (c);
where all the beasts of the field play; skip and dance, and delight in each other, being in no fear of behemoth; whether understood of the elephant or river horse; since neither of them are carnivorous creatures that feed on other animals, but on grass only; and therefore the beasts of the field may feed with them quietly and securely. Pliny (d) says of the elephant, that meeting with cattle in the fields, it will make signs to them not to be afraid of it, and so they will go in company together.
(a) Olaus Magus ut supra, (De Ritu. Septent. Gent.) l. 21. c. 19. Vid. Bochart. ut supra, (Apud Hierozoic. par. 2. l. 5. c. 14.) col. 763. Eden's Travels, p. 318. (b) See the North West Fox, p. 232. Voyage to Spitzbergen, p. 115, 120. Supplement, p. 194. (c) Olaus Magnus, ut supra, (De Ritu. Septent. Gent. l. 21. c. 19.) & Eden's Travels, ut supra. (p. 318.) (d) Nat. Hist. l. 8. c. 7.

The 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.

Mountains - Though he lives most in the water, yet he often fetches his food from the land, and from the mountains or hills, which are nigh the river Nile. Play - They not only feed securely, but sport themselves by him, being taught by experience that he is gentle and harmless.