(He is) the Lord of the two easts (places of sunrise during early summer and early winter) and the Lord of the two wests (places of sunset during early summer and early winter)
He is the Rabb of the two easts (the world and the eternal life after death) and the Rabb of the two wests (the world and the dimension of the grave).
Al-muntakhab fi tafsir al-Qur'an al-Karim
It is He, Who ordained the two major cardinal eastern points and the two major western cardinal points and the points in between, where the sun rises and sets in winter and summer respectively, passing through recurrent cycles of successive events