The correct way to describe the sun is that it “prostrates beneath the Throne” and not that it “sets in a spring of warm water”

Firstly: 

The hadeeth of Abu Dharr (may Allah be pleased with him) which describes the place where the sun goes was narrated via Ibraaheem ibn Yazeed at-Taymi, from his father, from Abu Dharr, from the Prophet (blessings and peace of Allah be upon him. 

It was narrated from Ibraaheem at-Taymi by al-Hakam ibn ‘Utaybah, al-A‘mash, Fudayl ibn Ghazwaan, Haroon ibn Sa‘d, and Moosa ibn al-Musayyab, as was stated by Ibn Mandah in al-Eemaan (2/926) 

They narrated it via two isnaads: 

The first isnaad: 

It was narrated by al-A‘mash, Yoonus ibn ‘Ubayd, Moosa ibn al-Musayyab and Haroon ibn Sa‘d. In this report it says that the sun goes and prostrates beneath the Throne or before its Lord; there is no mention of a spring of warm water. It appears in several versions, of which we will mention one here: 

It was narrated that Abu Dharr (may Allah be pleased with him) said: The Prophet (blessings and peace of Allah be upon him) said to Abu Dharr when the sun set: “Do you know where it goes?” I said: Allah and His Messenger know best. He said: “It goes and prostrates beneath the Throne, then it asks for permission (to rise) and permission is given to it. Soon it will prostrate, but it will not be accepted from it, and it will ask for permission (to rise) but permission will not be given to it; it will be said to it: “Go back to where you came from.’ So it will rise from its place of setting, and that is what Allah, may He be glorified, refers to in the verse (interpretation of the meaning): “And the sun runs on its fixed course for a term (appointed). That is the Decree of the All-Mighty, the All-Knowing” [Yaa-Seen 36:38]. 

It was narrated via A‘mash by al-Bukhaari in his Saheeh (no. 3199, 4802 and 7424); Muslim in his Saheeh (no. 159); Abu Dawood at-Tayaalisi in al-Musnad (1/368); Ahmad in al-Musnad (35/282, 429); at-Tirmidhi in as-Sunan (no. 2186, 3227 – he said: It is hasan saheeh; an-Nasaa’i in as-Sunan al-Kubra (10/229); at-Tabari in Jaami‘ al-Bayaan, 20/516); al-Bazzaar in al-Bahr al-Zukhaar (9/409); Abu ‘Awaanah in al-Mustakhraj (1/100-101); at-Tahhaawi in Sharh Mushkil al-Athaar (1/254); Ibn Hibbaan in his Saheeh (14/24); al-Qutay‘i in Juz’ al-Alf Dinar (p. 183); Abu Nu‘aym in al-Musnad al-Mustakhraj ‘ala Saheeh Muslim (1/222); al-Baghawi in at-Tafseer (4/14); Abu ash-Shaykh in al-‘Azamah (4/1192); Ibn Mandah in al-Eemaan (2/924) and at-Tawheed (1/134, 135); Ibn Bashraan in al-Amaali (p. 159); al-Bayhaqi in al-Asma wa as-Sifaat (2/273); Ibn ‘Asaakir in al-Mu‘jam (2/1015); Abu Nu‘aym in Hilyat al-Awliya’ (4/216) and others. 

It was narrated via Yoonus ibn ‘Ubayd by Imam Muslim in his Saheeh (no. 159); an-Nasaa’i in as-Sunan al-Kubra (10/96); at-Tabari in Jaami‘ al-Bayaan (12/249); Abu ‘Awaanah in al-Mustakhraj (1/100); Abu al-‘Abbaas as-Siraaj in Hadeeth as-Siraaj (3/258); Ibn Hibbaan  in his Saheeh (14/21); Abu ash-Shaykh in al-‘Azamah (4/1189); Ibn Mandah in al-Eemaan (2/925, 926) and in at-Tawheed (1/136); Abu Nu‘aym in al-Mustakhraj (1/221). 

It was narrated via Moosa ibn al-Musayyab by: Abu ash-Shaykh al-Asbahaani in al-‘Azamah (4/1188);

And via Haroon ibn Sa‘d by at-Tabaraani in al-Mu‘jam al-Kabeer (4/373); Abu ash-Shaykh al-Asbahaani in al-‘Azamah (4/1190). 

Abu Nu‘aym (may Allah have mercy on him) said: 

This is a saheeh hadeeth on which they (the hadeeth scholars) are agreed, from the hadeeth of al-A‘mash from Sufyaan ath-Thawri and others. It was narrated from at-Taymi al-Hakam ibn ‘Utaybah, Fudayl ibn ‘Umayr, Haaroon ibn Sa‘d, Moosa ibn al-Musayyab, Habeeb ibn Abi al-Ashras, and from Yoonus ibn ‘Umayd among the Basris.

End quote from Hilyat al-Awliya’ (4/216) 

The second isnaad: 

It was narrated by al-Hakam ibn ‘Utaybah only, from Ibraaheem at-Taymi; in this report it says that the sun sets in a spring of warm water. 

It was narrated that Abu Dharr said: I was riding behind the Messenger of Allah (blessings and peace of Allah be upon him) when he was on a donkey and the sun was setting. He said: “Do you know where this (sun) sets?” I said: Allah and His Messenger know best. He said: “It sets in a spring of warm water (innaha taghrubu fi ‘aynin haamiyah).”

Narrated by Ahmad in al-Musnad (35/363); Abu Dawood in as-Sunan (no. 4002); Hafs ad-Doori in Juz’ Qiraa’aat an-Nabi sall Allahu ‘alayhi wa sallam (p. 123); al-Bazzaar in al-Bahr al-Zakhaar (9/407); as-Siraaj in his Hadeeth (3/258); al-Haakim in al-Mustadrak (2/267) – he said: This is a hadeeth with a saheeh isnaad, although they (al-Bukhaari and Muslim) did not narrate it. All of them narrated it via Yazeed ibn Haaroon, from Sufyaan ibn Husayn, from al-Hakam. 

Al-Bazzaar said: We do not know that anyone narrated it from al-Hakam ibn ‘Utaybah, from Ibraaheem, from his father, from Abu Dharr except Sufyaan ibn Husayn. Yoonus ibn ‘Ubayd narrated it from Ibraaheem at-Taymi, Sulayman al-A‘mash and Haroon ibn Sa‘d. End quote. 

Secondly: 

From the above it is clear that the version of the hadeeth of Abu Dharr which is most likely to be correct is the first one, in which it says: “It goes and prostrates beneath the Throne”, in which it makes no mention of it setting “in a spring of warm water (innaha taghrubu fi ‘aynin haamiyah).” This is based on several factors: 

~1~

This wording is that on which the majority of narrators and those with the best memories agreed upon, in the report from Ibraaheem at-Taymi. 

~2~

The second version (“in a spring of warm water”) was narrated only by al-Hakam ibn ‘Utaybah from Ibraahem, and al-Hakam – although he was trustworthy – was described by an-Nasaa’i as mudallis [i.e., he used vague wording to give a wrong impression] in Dhikr al-Mudalliseen (no. 11). Ibn Hibbaan said: He used to engage in tadlees. End quote from ath-Thiqaat (4/144). None of those who narrated his hadeeth said that he clearly stated that he heard it from the previous narrator; rather they all said that his report included the word ‘an (from – instead of ‘I heard’, etc). Ibn Hajar mentioned him in Maraatib al-Mudalliseen in the second rank of mudalliseen (p. 30), who are the ones whose tadlees the imams (leading scholars) tolerated and from whom they narrated reports that they regarded as sound, because of their prominence and because they rarely engaged in tadlees  compared to others, such as ath-Thawri; or (it was tolerated) because they did not use engage in tadlees except when narrating from a trustworthy source, such as Ibn ‘Uyaynah. The fact that this report is contrary to the report narrated by the trustworthy narrators confirms the possibility that tadlees occurred in this hadeeth in particular. 

~3~

The first version was narrated by both al-Bukhaari and Muslim, whereas the second version was not narrated by these two shaykhs. That is because they thought the first version was more likely to be correct than any other. Undoubtedly the reports in the books of al-Bukhaari and Muslim take precedence, according to the critics and scholars, than those in other books and Musnads. 

~4~

There is a great difference between the two versions. The first one describes the sun as prostrating beneath the Throne, whether at the time of sunset or at any other time, according to different versions of the hadeeth. Prostration beneath the Throne is a matter of the unseen, and no one knows how it is except Allah, may He be glorified and exalted. He, may He be glorified and exalted, has told us that all created things prostrate to Him, as He says (interpretation of the meaning):

“See you not that to Allah prostrates whoever is in the heavens and whoever is on the earth, and the sun, and the moon, and the stars, and the mountains, and the trees, and Ad-Dawab (moving living creatures, beasts, etc.), and many of mankind? But there are many (men) on whom the punishment is justified”

[al-Hajj 22:18].

No one knows how this prostration is or when it happens or its real nature except Allah, may He be glorified and exalted. Similarly, the hadeeth of Abu Dharr is no different from this verse at all, and there is nothing objectionable in it. 

Al-Khattaabi (may Allah have mercy on him) said:

It cannot be denied that it halts beneath the Throne, in a manner that we cannot see or comprehend; rather this is speaking about a matter of the unseen. So we should not disbelieve in it or ask how it happens, because our knowledge cannot comprehend it.

End quote from A‘laam al-Hadeeth Sharh Saheeh al-Bukhaari (p. 1893) 

With regard to the second version, “It sets in a spring of warm water”, this is problematic, because the setting of the sun occurs when its disc disappears below the horizon, and it sets on some people and rises on others because of the movement of the earth around it. So it is not possible that the sun, which is of immense size, could disappear into a spring of warm water. With regard to the words of Allah, may He be exalted, in the story of Dhu’l-Qarnayn (interpretation of the meaning): “Until, when he reached the setting place of the sun, he found it setting in a spring of black muddy (or hot) water” [al-Kahf 18:86], the commentators said that what is meant is to depict the scene that appeared before him, for he saw it on the horizon of the sea, as if it were sinking into it at the time of setting. The Holy Qur’an does not tell us that this was something that happnened in a real sense; hence Allah, may He be glorified, said “he found it setting” and He did not say “it was setting in a spring of black muddy (or hot) water.” 

Al-Haafiz Ibn Katheer (may Allah have mercy on him) said:

That is, he way he saw the sun was as if it was setting in the ocean, which is something that happens to everyone who stands on the shore: he sees the sun as if it is setting into the sea, when in fact it does not leave the celestial path on which it is firmly established.

End quote from Tafseer al-Qur’an al-Kareem (5/191) 

To sum up: whoever casts aspersions on the Sunnah because of this wording is ignorant of the precision of the hadeeth scholars in examining different versions of the hadeeth and distinguishing between the reports which are proven and those which are not proven. The fact that some scholars regarded this report as saheeh is problematic; rather what they intended was to class as saheeh the basis of the hadeeth, not to suggest that this version is more correct than that which is proven in as-Saheehayn: “It goes and prostrates beneath the Throne.” 

In order to refute this specious argument, it is sufficient to note that the scholars of Islam were unanimously agreed that the earth is round and that all the celestial bodies are also round. It is on that basis that night and day alternate, because of the movements and rotation of these heavenly bodies. This is clear from many texts of the Qur’an and Sunnah. 

Ibn Taymiyah (may Allah have mercy on him) said: 

The heavenly bodies are round, according to the Muslim scholars among the Sahaabah and those who followed them in guidance; that was also proven from them with isnaads mentioned in the appropriate places. In fact, more than one of the Muslim scholars narrated that there was consensus among the Muslims on that point.

End quote from Minhaaj as-Sunnah an-Nabawiyyah (5/442) 

The Muslims were ahead of others in knowledge of astronomy; if the apparent meaning of this hadeeth contradicts that, then there would not have been consensus on the contrary; but the correct view is that the hadeeth does not contradict the scientific, astronomical facts. 

And Allah knows best.