2 Kings 13:17
And he said, Open the window eastward. And he opened it. Then Elisha said, Shoot. And he shot. And he said, The arrow of the LORD’s deliverance, and the arrow of deliverance from Syria: for thou shalt smite the Syrians in Aphek, till thou have consumed them.
The arrow shot eastward was a sign of the Lord's deliverance from Syria, declaring that Joash would smite the Syrians at Aphek until they were consumed. That promised deliverance included the freeing of the cities beyond the Jordan that Syria held. The promise gave the king an opportunity to make up for past failures, with God again acting on behalf of erring Israel.
Elisha's direction to open the window and shoot showed trust in God's power and forward movement by faith when the way seemed closed, a confidence God honored by opening the way. The fulfillment of the victory depended on the king's persevering faith, as the following test of striking the ground revealed, and because Joash struck only sparingly his victories would be limited. When God opens the way and assures success, those entrusted with His work must act with energy and perseverance to bring about the promised result.