Eastward; either towards Syria, which lay north-eastward from the land of Israel; or towards the Israelites land beyond Jordan, which lay eastward from Canaan, and which was now possessed by the Syrians. Either way this arrow is shot against the Syrians, as a token what God intended to do against them. In Aphek; not in the city, but in the territory of it, where it seems there was a great battle to be fought between the Israelites and Syrians. Of Aphek, see 1 Samuel 4:1, 1 Samuel 29:1 1 Kings 20:30, though it is possible there might be several cities of that name. Or, as in Aphek, i.e. thou shalt smite them as they were smitten in the city and territory of Aphek, i.e. utterly destroy them; see 1 Kings 20:26,29,30; the particle as being oft understood, as hath been formerly and frequently proved. Till thou have consumed them, i.e. the Syrians; not all that people, but their armies, or at least that which was to be at Aphek, where a dreadful battle was to be fought. Or if this be meant of all the Syrian armies, this is to be understood conditionally, if he did not hinder it by his unbelief or neglect, signified in the following verses.
Related Commentaries of 2 Kings 13:17
2 Kings 13:17
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.