Till, when he reached the setting-place of the sun, he found it setting in a muddy spring, and found a people thereabout. We said: O Dhu'l-Qarneyn! Either punish or show them kindness. First of all there's no ONE place where the sun sets since the earth is spherical. Second why do tafsirs of this verse add their opinions about what it means. Lastly, Muslims claim that since wajada can mean false or true perception,Dhul qurnanyn was clearly falsely perceiving the sun setting on the murky water. However the preceding verse clearly states that this is the place where the Sun sets. So how can he be wrong when he is in the right place ?
When Allah says ⟪he reached the setting-place of the sun⟫, the meaning is that he reached the westernmost region that was accessible to him, either this was Western Africa (like Morocco) or (less probably) Western Europe.
It is called ⟪the setting-place of the sun⟫ for one of two reasons.
Firstly, you need to understand Arabic directions. In Arabic, there are no independent words for east and west. Rather, east is called mashriq (rising-place) and west is called maghrib (setting-place).
These are obviously short for "rising-place of the sun" and "setting-place of the sun," and they are called this because east is where the sun rises and west is where the sun sets.
Usually, you just say "rising-place" or "setting-place" in normal speech if you want to say east or west.
But, in this verse, Allah chose to say the full phrase "setting-place of the sun," and this can be for different reasons which I will not go into. One possibility is it is more poetic than to say:
حَتّى إذا بَلَغَ المَغْرِبَ وجَدَ الشَمْس تَغْرُبُ في عَيْنٍ حَمِئَةٍ
So, although Allah says ⟪the setting-place of the sun⟫, that should just be taken as long for "west." So, he reached the west and found the sun setting in a muddy spring.
Secondly, it is possible Allah termed the westernmost portion of land Dhul-Qarnayn reached "the setting-place of the sun" for the same reason we might call places "sunset point" or "sunset beach." It was considered prominent as the furthest place where you can see the sun set.
Even today, Morocco in Arabic is called "Maghrib," literally "setting-place" or "west."
tafsirs of this verse add their opinions about what it means
The point of tafsir is to give their opinions on what the Quran means.
Muslims claim that since wajada can mean false or true perception,Dhul qurnanyn was clearly falsely perceiving the sun setting on the murky water
Although it is true that wajada can mean false or true perception, Dhul-Qarnayn is perceiving things truly here.
The whole concept of the sun setting is perceptual. It, by definition, refers to our perception of the sun. So, saying the sun set into a muddy spring is already talking about our perception, and it is true as long as he did actually see the sun set into the muddy spring. It has nothing to do with falsehood.
When we say the sun set into a spring or the sea or anything else, the word "set" already refers to the sun (in our perception) going into that thing. People do not normally use the word "set" to refer to the sun physically entering anything.
And Allah knows best.