Tafsir of As-Saffat 37:87

(Meaning: What is your estimation regarding the One who is worthy of worship by virtue of being the Lord of the worlds? Have you doubted Him to the extent that you have abandoned His worship, Glorified be He, entirely? Or have you known what He is, to the extent that you have made idols partners unto Him, Exalted and Transcendent is He? Or what is your estimation regarding His punishment, Mighty and Majestic is He, that you have dared to fabricate lies against Him and have not feared?)

His people, peace be upon him, used to venerate the well-known celestial bodies and believed that prosperity, misfortune, good, and evil in the world originated from them. They would designate a temple for each of these planets and place within them idols that, according to their claims, corresponded to that planet. They made the worship and veneration of these idols a means toward worshipping those celestial bodies and invoking their spiritual influences. They used the positions of these planets to deduce cosmic events, whether general or specific.

It so happened that a day of their festival approached, on which they would go out, so their king sent to Abraham, peace be upon him, saying: "Tomorrow is our festival, so attend with us." He perceived that an opportunity had arisen for something that might serve as a cause for their monotheism, so he wanted to excuse himself from attending in a manner that would not allow them to reproach him.