All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
These two Ahaadeeth include two points:
The first point: The setting of the sun in a spring of black muddy water (or a spring of hot water). Before talking about the meaning of this statement, we must establish a fact that the sun does not set at a specific tangible place; rather, it sets in a specific direction which is what has been defined by the people by the term: the west. When the sun sets in relation to some people, it rises upon some other people and so on. This indicates that what is meant is not the literal meaning of the Hadeeth.
In his interpretation of the story of Thul-Qarnayn, and the verse in which Allaah says (what means): {Until, when he reached the setting of the sun, he found it [as if] setting in a spring of dark mud,…} [Quran 18:86], Al-Qurtubi quoted Al-Qaffaal as saying: “Some scholars said: what is meant is not that Thul-Qarnayn reached the west where the sun itself sets or the east where the sun itself rises, because it revolves in the sky around the earth without touching the earth. The sun is much bigger than the earth, so how can it enter at a place of the places of the earth? Rather, what is meant is that he reached the farthest point of the west, and the farthest point of the east, and he found it, according to what the eye can see, as if it sets in a spring of black muddy water, in the same manner that we see it in the desert as if it enters into the inside of the earth.” [End of quote] This means in relation to how the eye sees it.”
The second point: Its prostration under the Throne. This was interpreted by the scholars in many ways. For instance, Ibn Hajar said: “It is likely that what is meant by prostration is the prostration of the angels that are in charge of it, or that it itself prostrates, which means showing more submission and humility at that time.”
The most preponderant opinion is that it is a real prostration and we do not know how it is done. Shaykh Muhammad Saalih Al-Munajjid said: “Its prostration is real in a manner befitting the sun, but how does it fall prostrate before Allaah under the Throne? Only Allaah knows how this prostration takes place. The apparent meaning of the Hadeeth does not suggest that prostration refers to mere submission to the order of Allaah and being subjugated to His Obedience. Rather, it is submission, humiliation and compliance with a real prostration but we do not know how it is done. The same thing is said about the moon, trees, animals and all other beings, as each of them has its own manner of prostration that suits it. Therefore, a Muslim should not let his ignorance of how all these creations prostrate prevent him from believing in what Allaah informed us about the prostration of created beings to Him."
Allaah Knows best.