2 Kings 16:7

So Ahaz sent messengers to Tiglath-pileser king of Assyria According to 2 Chron. (2 Chronicles 28:17-18) it was not only by Rezin of Damascus and Pekah of Israel that Ahaz was straitened when he sent for help to Assyria. -The Edomites had again come and smitten Judah, and carried away captives. The Philistines also had invaded the cities of the low countries, and of the south of Judah, and had taken Beth-shemesh and Ajalon with Gederoth, and Socho with the villages thereof, and Timnah likewise and Gimzo, and they dwelt there." So that on north and south alike Ahaz was sorely beset. -For the Lord brought Judah low, because of Ahaz, for he made Judah naked, and transgressed sore against the Lord".

I am thy servant and thy son Ahaz, in return for the help he seeks, offers to make himself the vassal of Assyria. With the name -son", as used in such an address, may be compared the -brother" which Ahab uses of the conquered Benhadad (1 Kings 20:32). Ahaz in his petition naturally only mentions those enemies on the north upon whom Tiglath-pileser could most readily fall. Perhaps he felt that, if relieved from them, he could dispose of the Edomites and Philistines by his own power.