At the blast of the horn, he snorts with fervor. He catches the scent of battle from afar, the shouts of captains and the cry of war.
God, having displayed his own power in those creatures that are strong and despise man, here shows it in one scarcely inferior to any of them in strength, and yet very tame and serviceable to man, and that is the horse, especially the horse that is prepared against the day of battle and is serviceable to man at a time when he has more than ordinary occasion for his service.
Commenting on Job 39:19-25
He saith among the trumpets, ha, ha,.... As pleased with the sound of them, rejoicing thereat, and which he signifies by neighing; and he smelleth the battle afar off; which respects not so much the distance of place as of time; he perceives beforehand that it is near, by the preparations making for it, and particularly by what follows; so Pliny (b) says of horses, they presage a fight.
saith--poetically applied to his mettlesome neighing, whereby he shows his love of the battle. smelleth--snuffeth; discerneth (Isa 11:3, Margin). thunder--thundering voice.