Therefore the LORD shall set up the adversaries of Rezin against him, and join his enemies together; The adversaries of Rezin against him "The princes of Retsin against him" - For צרי tsarey, enemies, Houbigant, by conjecture, reads שרי sarey, princes; which is confirmed by thirty of Kennicott's and De Rossi's MSS., (two ancient), one of my own, ancient; and nine more have צ tsaddi, upon a rasure, and therefore had probably at first שרי sarey. The princes of Retsin, the late ally of Israel, that is, the Syrians, expressly named in the next verse, shall now be excited against Israel.
The Septuagint in this place give us another variation; for רצין Retsin, they read הר ציון har tsiyon, ορος Σιων, Mount Sion, of which this may be the sense; but Jehovah shall set up the adversaries of Mount Sion against him, (i.e., against Israel), and will strengthen his enemies together; the Syrians, the Philistines, who are called the adversaries of Mount Sion. See Simonis Lex. in voce סכך sachach.