Prophet Hud - 11:109
Have no doubt about those whom they serve. They serve just as their forefathers served before. We will pay them their portion in full.
What is the punishment for worshipping/serving other than Allah?
The Table Spread/5:72
"Those who say: "Allah is the Messiah, son of Mary,"have certainly disbelieved. But the Messiah said, "Children of Israel, serve Allah, my Lord and your Lord. Whoever associates partners with Allah, Allah forbids him Paradise, and his abode will be the Fire. And there will be no helper for the wrongdoers."
The Women/4:48
Allah does not forgive associating partners with Him, but other than that He forgives to whom He wills. Whoever associates partners with Allah has committed a great insult.
The Women/4:116
Allah does not forgive associating partners with Him (if it continues until death), but He forgives the sins below that to whom He wills. Whoever associates partners with Allah has gone astray.
The Night Journey/17:22
Do not take other gods along with Allah, lest you remain condemned and left alone.
The Night Journey/17:39
These are among the wisdoms that your Lord has revealed to you. Do not take other gods along with Allah; otherwise you will be cast into Hell, condemned and cast out.
The Pilgrimage/22:31
Dedicate yourselves to Him alone, associating no partners with Allah. Whoever associates partners with Allah, it is as if he has fallen from the sky and has been seized by a vulture, or is being carried away by the wind in a deep fjord.
Luqman/31:13
"When Lokman advised his son, he said: "My dear son, do not associate partners with Allah; surely shirk (associating partners with God) is a great wrong."
The Companies/39:65
It has been revealed to you and those before you that if you associate partners, all that you do will be in vain and you will be of the losers.