Allah declares Himself to be above having any child or partner in dominion, control and worship. He says:
No son did Allah beget, nor is there any god along with Him. (If there had been many gods), then each god would have taken away what he had created, and some would have tried to overcome others.
meaning, if it were decreed that there should be a plurality of deities, each of them would have exclusive control over whatever he had created, so there would never be any order in the universe. But what we see is that the universe is ordered and cohesive, with the upper and lower realms connected to one another in the most perfect fashion.
you can see no fault in the creation of the Most Gracious 65:3.
Moreover, if there were a number of gods, each of them would try to subdue the other with enmity, and one would prevail over the other. This has been mentioned by the scholars of 'Ilm-ul-Kalam who discussed it using the evidence of mutual resistance or counteraction. This idea states that if there were two or more creators, one would want to make a body move while the other would want to keep it immobile, and if neither of them could achieve what they wanted, then both would be incapable, but the One Whose existence is essential [i.e., Allah] cannot be incapable. It is impossible for the will of both to be fulfilled because of the conflict. This dilemma only arises when a plurality of gods is suggested, so it is impossible for there to be such a plurality, because if the will of one is fulfilled and...