Az-Zumar 39:64

Allah is the Creator and Controller, and associating others in worship with Him cancels out Good ...

Allah tells us that He is the Creator, Lord, Sovereign and Controller of all things; everything is subject to His dominion, power and guardianship.

لَّهُ مَقَالِيدُ السَّمَـوَتِ وَالاٌّرْضِ

(To Him belong the Maqalid of the heavens and the earth.) Mujahid said, "Maqalid means `keys' in Persian." This was also the view of Qatadah, Ibn Zayd and Sufyan bin `Uyaynah. As-Suddi said:

لَّهُ مَقَالِيدُ السَّمَـوَتِ وَالاٌّرْضِ

(To Him belong the Maqalid of the heavens and the earth.) "The treasures of the heavens and the earth." Both opinions mean that the control of all things is in the Hand of Allah, may He be blessed and exalted, for His is the dominion and to Him is the praise, and He is able to do all things. He says:

وَالَّذِينَ كَفَرُواْ بِـَايَـتِ اللَّهِ

(And those who disbelieve in the Ayat of Allah,) meaning, His proof and evidence,

أُولَـئِكَ هُمُ الْخَـسِرُونَ

(such are they who will be the losers.)

قُلْ أَفَغَيْرَ اللَّهِ تَأْمُرُونِّى أَعْبُدُ أَيُّهَا الْجَـهِلُونَ

(Say: "Do you order me to worship other than Allah O you fools!") The reason for the revelation of this Ayah was narrated by Ibn Abi Hatim and others from Ibn `Abbas, may Allah be pleased with him, that the idolators in their ignorance called the Messenger of Allah ﷺ to worship their gods, then they would worship his God with him. Then these words were revealed:

قُلْ أَفَغَيْرَ اللَّهِ تَأْمُرُونِّى أَعْبُدُ أَيُّهَا الْجَـهِلُونَ - وَلَقَدْ أُوْحِىَ إِلَيْكَ وَإِلَى الَّذِينَ مِن قَبْلِكَ لَئِنْ أَشْرَكْتَ لَيَحْبَطَنَّ عَمَلُكَ وَلَتَكُونَنَّ مِنَ الْخَـسِرِينَ

(Say: "Do you order me to worship other than Allah O you fools!" And indeed it has been revealed to you, as it was to those before you: "If you join others in worship with Allah, surely your deeds will be in vain, and you will certainly be among the losers.") This is like the Ayah:

وَلَوْ أَشْرَكُواْ لَحَبِطَ عَنْهُمْ مَّا كَانُواْ يَعْمَلُونَ

(But if they had joined in worship others with Allah, all that they used to do would have been of no benefit to them.) (6:88).

بَلِ اللَّهَ فَاعْبُدْ وَكُن مِّنَ الشَّـكِرِينَ

(Nay! But worship Allah, and be among the grateful.) means, `you and those who follow you and believe in you should make your worship sincerely for Allah Alone, with no partner or associate.'

Tafsir Ibn Kathir (abridged, English).