Job 39:25 - Matthew Poole's English Annotations on the Holy Bible

Ha, ha; an expression of joy and alacrity, declared by his proud neighings; whereby he doth in some sort answer the sound of the trumpets, in way of scorn and challenge. He smelleth, i.e. he perceiveth, as this phrase is used, Judges 16:9. Afar off; at some distance, either of place, or rather of time, as the word is most frequently used. He perceives by the motion of the soldiers, and the clattering of the arms, that the battle is at hand, which is very welcome to him. The thunder of the captains; by which he understands, either the military orations which the captains make and deliver with a loud voice to animate their soldiers to the battle; or rather the loud and joyful clamour begun by the commanders, and followed by the soldiers, when they are ready to join battle, that thereby they may both daunt their enemies, and encourage themselves.