The sense is either,
1. He is so earnest and eager upon the battle, that he rusheth into it with all speed; and runs over the ground so swiftly, that he might seem to have swallowed it tap. Or,
2. He is so full of war-like rage and fury, that he not only champs his bridle, but is ready to tear and devour the very ground on which he goes. And the phrase here used is not unusual, both in Arabic and in other authors; of which see my Latin Synopsis on this place. He is so pleased with the approach of the battle, and the sound of the trumpet calling to it, that he could scarce believe his cars for gladness: compare Genesis 45:26 Luke 24:41. Or thus, he cannot stand still, or firm, (as this verb and Hie derivative from it is used, not only in the Chaldee and Syriac dialect, but also in the Hebrew, as Deuteronomy 28:59 1 Samuel 2:35) when the trumpet soundeth; his rider can hardly keep him still, but he strives and longs to run to the fight.