Heshbon, the chief city of the Amorite king, Sihon. Some ruins on a hill east of the upper end of the Dead Sea, and bearing the name Chesban, mark the site of this once large and important city. Sihon rejected Moses' overtures of peace, because God had hardened his spirit, and made his heart obstinate; literally, had sharpened his heart, had made his determination keen.
It is not to be supposed that any influence was directly exerted on him, to make him obdurate and persistent in his hostility to the people of God; the expression "he would not" indicates that it was of his own will that Sihon acted; but it was the will and purpose of God that Sihon should be destroyed, and his country taken by the Israelites, and so he was placed in circumstances by which, "given over to a reprobate mind," he was confirmed and strengthened m his determination to pursue a course which led to his destruction; like Pharaoh, by the circumstances in which God placed him, he found scope for the display and for the confirmation of a stubborn, pertinacious pride of spirit, which led ultimately to his ruin.
Nothing so hardens the heart as resistance to God's overtures of peace. As appeareth this day; i.e. as present experience shows; in Sihon's refusing to let them pass, there was already an actual beginning of the fulfillment of God's purpose to deliver him into the hand of the Israelites.