Sahih Muslim 159c

Abu Bakr ibn Abi Shayba and Abu Kurayb narrated to us—the wording is Abu Kurayb's. They said: Abu Mu'awiya narrated to us; al-A'mash narrated to us, from Ibrahim al-Taymi, from his father, from Abu Dharr, who said: I entered the mosque while the Messenger of Allah (peace and blessings be upon him) was sitting there. When the sun had set, he said: Abu Dharr, do you know where it goes? I said: Allah and His Messenger know best. He said: It goes and seeks permission to prostrate, and permission is granted. It is as though it is told: Return to where you came from. Then it will rise from its place of setting. He then recited, in 'Abdullah's recitation: And that is its appointed course.