1 Kings 12:33

So he offered upon the altar which he had made in Bethel the fifteenth day of the eighth month, even in the month which he had devised of his own heart, without the command of Jehovah; and ordained a feast unto the children of Israel, to take the place of at least one of the great festivals commanded by Jehovah; and he offered upon the altar and burned incense, he deliberately planned and made ready to take part in the worship which he had instituted. All apparent worship of Jehovah which men devise in their own hearts, all sacrifices and works which are made by the commandment of men and are intended to merit the favor of God are an abomination before the Lord and a transgression of the First Commandment.