Some refer this to what went before, as a reason why the Jews should return, for God hath commanded it. I think it is an encouragement to the Jews to return, because God had promised to make them a glory, and now assures them that he will take a very particular care of them, therefore sends his Son, as a Judge or Vindex against the nations that had spoiled the Jews; or God sends his Son to them to inform them that it is their interest to unite with the Jews, and become the people of God, and be partakers of the glory and safety of God's Israel; however, to let them understand that it will be dangerous to do violence to Israel, as it would be dangerous to any one to violate what is most dear to him that can destroy the offender; to tell them Israel is the apple of God's eye.
Related Commentaries of Zechariah 2:8
Zechariah 2:8
8 For thus saith the LORD of hosts; After the glory hath he sent me unto the nations which spoiled you: for he that toucheth you toucheth the apple of his eye.