Sahih Bukhari | Volume 6 | Hadith Number 326

Narrated by Abu Dharr
Once I was with the Prophet in the mosque at the time of sunset. The Prophet said, "O Abu Dharr! Do you know where the sun sets?" I replied, "Allah and His Apostle know best." He said, "It goes and prostrates underneath (Allah's) Throne; and that is Allah's Statement:

'And the sun runs on its fixed course for a term (decreed). And that is the decree of All- Mighty, the All-Knowing...' (36:38)