I Kings 12-13. I find it interesting in 1 Kings 12 that Israel fell apart like this. Rather than overthrow the King they just left. I guess the Bible tells us why in verse 24: "This is what the Lord says: 'Do not go up to fight against your brothers the Israelites. Go home every one of you, for this is my doing.'"
It's very sad how willingly the people accepted the golden calves in place of a living God.