Rabbu assamawati wal-ardi wama baynahuma warabbu almashariq (surah Assaaffat: 5)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(37:5) the Lord of the heavens and the earth and of whatever lies between the two, the Lord *3 of the Easts. *4

Rabbus samaawaati wal ardi wa maa bainahumaa wa Rabbul mashaariq

*3) The Truth that has been conveyed in these verses is: "The Master and Ruler of the Universe is the real Deity of men: He alone can be, and should be, the .Deity. It would be utterly irrational that the Rabb (i.e.. Master, Ruler, Guardian and Sustainer) of the man should be one but his Ilah (deity) another. The basic reason for worship is that man should naturally bow down before and acknowledge the superiority of him who can bring him harm and good, who can fulfil his needs and requirements, who can make or mar his destiny and has power over his life and survival itself. If man understands this he will automatically understand that to worship the one who has no power and not to worship Him Who has All the powers arc both against reason and nature. The One Who alone is worthy of worship is He Who possesses the powers. As far as the powerless beings are concerned, they are neither worthy of worship, nor is it in any way profitable to worship and pray to them, for it is not in their power to take any action whatever on man's petitions and prayers. To bow before them humbly and to petition them would be as foolish and meaningless an act as to bow before and petition another one who has himself gone before a ruler to make obeisance and submit his petitions.
*4) The sun dces not always rise at the same point but at a different point every day. Moreover, it dces not rise at one and the same time for the whole world but rises at different times for the different parts of the earth. That is why the plural "Mashariq" (Easts) has been used to indicate the different points at which the sun rises according to the season of the year. The corresponding word 'Magharib" (Wests) has not been used because Mashariq itself points to Magharib However, in Surah Al-Ma'arij, the word magharib also has been used along with tnashariq: Rabb-al-mashariqi wal-magharib.