(Say: O disbelievers! …) [109:1-6].
These verses was revealed about a group of people from the Quraysh who said to the Prophet, Allah bless him and give him peace: “Come follow our religion and we will follow yours. You worship our idols for a year and we worship you Allah the following year. In this way, if what you have brought us is better than what we have, we would partake of it and take our share of goodness from it; and if what we have is better than what you have brought, you would partake of it and take your share of goodness from it”. He said: “Allah forbid that I associate anything with Him”, and so Allah, exalted is He, revealed (Say: O disbelievers!) up to the end of the Surah. The Messenger of Allah, Allah bless him and give him peace, then went to the Sacred Sanctuary, which was full of people, and recited to them the Surah. It was at that point that they despaired of him.
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou