2 Kings 13:17. He said, Open the window eastward. And he opened it. Then Elisha said, Shoot. And he shot.
This was an ancient method of declaring war, and is often referred to in ancient and classical writings. A herald came to the confines of the enemy’s territory, and, after observing certain solemnities, cried with a loud voice, “I wage war against you,” at the same time assigning the reasons for the war. He then shot an arrow or threw a spear into the country to be invaded, which was considered sufficient warning of warlike intentions. Thirty days were allowed for peaceable settlement; if no such settlement was reached during that time, hostilities began at the expiration of it.