1 Kings 12:33

33 On the fifteenth day of the eighth month, a month of his own choosing, he offered sacrifices on the altar he had built at Bethel. So he instituted the festival for the Israelites and went up to the altar to make offerings.

Read 1 Kings 12:33 Using Other Translations

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; and ordained a feast unto the children of Israel: and he offered upon the altar, and burnt incense.
He went up to the altar that he had made in Bethel on the fifteenth day in the eighth month, in the month that he had devised from his own heart. And he instituted a feast for the people of Israel and went up to the altar to make offerings.
So on the fifteenth day of the eighth month, a day that he himself had designated, Jeroboam offered sacrifices on the altar at Bethel. He instituted a religious festival for Israel, and he went up to the altar to burn incense.

What does 1 Kings 12:33 mean?

John Gill's Exposition of the Bible
1 Kings 12:33

So he offered upon the altar which he had made in Bethel the
fifteenth day of the eighth month
As he had done in Dan:

even in the month which he had devised of his own heart;
the feast of tabernacles was of God's appointing, but the time of keeping he had devised himself, changing it from the seventh month, or Tisri, which answers to our September and October, to the eighth month, or Marchesvan, which answers to part of October and part of November:

and ordained a feast unto the children of Israel;
to be observed by them as the feast of tabernacles was by the priests of Judah and Benjamin:

and he offered upon the altar, and burnt incense;
which none but the priests should do; perhaps the reason why the same resentment was not shown as to Uzziah was, because this was not at the altar of the Lord: whether he burnt incense after the manner of the Jewish priests, or as the priests of Egypt did to the sun, where he had been for some time, is not certain; the former burnt incense only twice a day, morning and evening, the latter three times; at sunrising they burnt rosin, about noon myrrh, and about sun setting "kuphi", which was a compound of sixteen sorts F23.


FOOTNOTES:

F23 Plutarch de lside & Osiride.
California - Do Not Sell My Personal Information  California - CCPA Notice