Until he reached the setting of the sun, and he found it setting at a boiling lake, and he found near it a people. We said, "O Two Eras, either you are to punish, or you are to do them good."
Translation endnotes
[18:86] This verse is among the handful verses cited by careless critics of the Quran as an example of scientific inaccuracies in the Quran. However, they ignore the obvious fact that the Quran describes the setting of the sun through the eyes of Zulqarnain. In other words, it is not used within the context of an objective scientific description but merely a perception of a person. A little search of the Internet will bring millions of occurrences of expressions such as "sun set" or "sun will set" or "sun sets". Of course, none accuses the author of those expressions of believing that the sun is rotating around the earth. Besides, the Arabic word for "sank" is "gharaqa" not "gharaba" (set) as is used in the verse. See 4:82.