The Cattle - 6:65
"Say: "He is able to send upon you a torment from above you or from beneath your feet, or to divide you into sects and make you taste the evil of one another."See how We make clear Our verses so that they may understand."
Sects are a divine punishment for abandoning the Qur'an:
The Cattle/6:159
You have nothing to do with those who divide their religion into parts and go in groups. Their affair is up to Allah; then He will inform them of their situation.
The Believers/23:53
But they divided their affairs into various books. Each group is content with what is with it.
The Romans/30:32
Those who have divided their religion into sects. Each party boasts of its own (Imam and book).
The Cattle/6:65
"Say: "He is able to send upon you a torment from above you or from beneath your feet, or to divide you into sects and make you taste the evil of one another."See how We make clear Our verses so that they may understand."
The Cattle/6:153
This is my straight path. Follow it and do not follow other ways, for they will lead you away from His Way. These are His admonitions to you that you may listen.