salam,
there is no hadith saying the sun sets in the murky spring, it was just from the perception of dhul qarnayn
i think i know which hadith you are using, but these hadith are not strong ad can be proven
Yazid bin Harun- Sufyan bin Husain- Al-Hakam bin ‘Utaybah- Ibrahim (b. Yazid al-Taymi)- Yazid al-Taymi- Abu Dharr said: I was sitting behind the Apostle of Allah who was riding a donkey while the sun was setting. He asked: Do you know where this sets? I replied: Allah and his Apostle know best. He said: It sets in a spring of warm water. (Sunan Abu Dawud, Hadith 3991)
Related narrations:
In Musnad Ahmad these words are part of a longer narration reported through same chain of narrators;
Abu Dharr narrated, “Once I was with the Prophet riding a donkey on which there was a saddle or a (piece of) velvet. That was at sunset. He said to me, ‘O Abu Dharr, do you know where this (sun) sets?’ I said, ‘Allah and His Messenger know better.’ He said, ‘It sets in a spring of murky water, (then) it goes and prostrates before its Lord, the Exalted in Might and the Ever-Majestic, under the Throne. And when it is time to go out, Allah allows it to go out and thus it rises. But, when He wants to make it rise where it sets, He locks it up. The sun will then say, “O my Lord, I have a long distance to run.” Allah will say, “Rise where you have set.” That (will take place) when no (disbelieving) soul will get any good by believing then.’” (Musnad Ahmad, Hadith 21459 al-Risala ed.)
why its weak and not correct, firstly our main and most authentic hadith book is bukhari and bukhari says:
In Sahih Bukhari it goes as;
Sufyan (al-Thawri)- Al-A’mash- Ibrahim (b. Yazid al-Taymi)- Yazid al-Taymi- Narrated Abu Dharr: The Prophet asked me at sunset, "Do you know where the sun goes (at the time of sunset)?" I replied, "Allah and His Messenger know better." He said, "It goes (i.e. travels) till it prostrates Itself underneath the Throne and takes the permission to rise again, and it is permitted and then (a time will come when) it will be about to prostrate itself but its prostration will not be accepted, and it will ask permission to go on its course but it will not be permitted, but it will be ordered to return whence it has come and so it will rise in the west. And that is the interpretation of the Statement of Allah: "And the sun is quickly proceeding towards its destination. That is the designing of the All-Mighty, the All-Knowing. " (36.38) (Sahih Bukhari, Volume 4, Book 54, Hadith 421)
The significant difference is of the words “it sets in a spring of warm/murky water.”
for the rest thorough and detailed refutation see:
http://www.letmeturnthetables.com/2012/09/weak-hadith-sun-spring-warm-water.html and this video from about 8:20 onwards:
https://www.youtube.com/watch?v=P7dSXbBdJko&t=493s and this video,
https://www.youtube.com/watch?v=SGU1nSbCaWYThis whole narrative of sun setting refuted thoroughly:
https://m.youtube.com/watch?v=Fc2NQMhP_pM and
https://m.youtube.com/watch?v=_RBKqyaaozk and
https://m.youtube.com/watch?v=P7dSXbBdJko and
https://m.youtube.com/watch?v=ZtQA2OH9Lbk and
https://m.youtube.com/watch?v=fF-FqnAzJ9M and
https://m.youtube.com/watch?v=JE-jDAqBiqg and
http://www.call-to-monotheism.com/sun_setting_in_murky_water___by_hesham_azmy_ and
http://thefactsaboutislam.blogspot.nl/2015/08/antimuslim-sun-set-arguments-refuted-by.html?m=1
with regard to tafasir, Imam Al-Baidawi notes,
He probably reached shore of the ocean and saw it like that because there was but water at the furthest of his sight that's why He says "he found it set" and does not say "it sets". (Al-Baidawi, Anwar-ut-Tanzil wa Asrar-ut-Taw'il, Volume 3, page 394. Published by Dar-ul-Ashraf, Cairo, Egypt)
Imam Al-Qurtubi states,
Al-Qaffal said: It is not meant by reaching the rising or setting of the sun that he reached its body and touched it because it runs in the sky around the earth without touching it and it is too great to enter any spring on earth. It is so much larger than earth. But it is meant that he reached the end of populated land east and west, so he found it - according to his vision - setting in a spring of a murky water like we watch it in smooth land as if it enters inside the land. That is why He said, "he found it rising on a people for whom we had provided no covering protection against the sun." (Holy Qur'ân 18:90) and did not mean that it touches or adheres to them; but they are the first to rise on.
Al-Qutabiy said: Probably this spring is a part of the sea and the sun sets behind, with or at it, so the proposition takes the place of an adjective and Allah knows best. (Al-Qurtubi, Al-Game' le Ahkam-el-Qur'an, Volume 16, page 47. Published by Dar-ul-Hadith, Cairo, Egypt. ISBN 977-5227-44-5)
Imam Fakhr-ud-Deen Ar-Razi states,
When Zul-Qarnain reached the furthest west and no populated land was left, he found the sun as if it sets in a dark spring, but it is not in reality. The same when sea traveler sees the sun as if it sets in the sea if he cannot see the shore while in reality it sets behind the sea. (Ar-Razi, At-Tafsir-ul-Kabir, Volume 21, page 166)
Imam Ibn Kathir states,
"Until, when he reached the setting of the sun" means he followed a certain way till he reached the furthest land he could go from the west. As for reaching the setting of the sun in the sky, it is impossible. What narrators and story tellers say about that he walked for a period of time in earth while the sun was setting behind him is unreal, and most of it is from myths of People of the Book and inventions of their liars.
"he found it set in a spring of murky water" means he saw the sun according to his vision setting in the ocean and this is the same with everyone ending to the shore seeing as if the sun sets inside it (i.e. the ocean).
(Ibn Kathir, Tafsir-ul-Qur'ân Al-'Azim, Volume 5, page 120. Published by Maktabat-ul-Iman, Mansoura, Egypt)
