Adam Clarke on 2 Kings 13:18

Smite upon the ground - As he was ordered to take his arrows, the smiting on the ground must mean shooting arrows into it.

He smote thrice, and stayed - The prophet knew that this shooting was emblematical: probably the king was not aware of what depended on the frequency of the action; and perhaps it was of the Lord that he smote only thrice, as he had determined to give Israel those three victories only over the Syrians. Elisha's being wroth because there were only three instead of five or six shots does not prove that God was wroth, or that he had intended to give the Syrians five or six overthrows.