Ahijah is the spokesman who announces judgment, but he speaks the words of God using the language, thus says the Lord, the God of Israel.
Jeroboam is told that he is to take ten of the twelve strips. God explains that he is about to take the rule of Israel away from the dynasty of David and Solomon. If this had been all, it would seem proper to leave the garment in one piece, but there is more to come. One tribe will remain under the authority of David’s house. This is for the sake of David, the one faithful king of Israel and for the sake of Jerusalem, where he chose to place the temple.
31 And he said to Jeroboam, “Take for yourself ten pieces, for thus says the LORD, the God of Israel, ‘Behold, I am about to tear the kingdom from the hand of Solomon and will give you ten tribes