And if the two agree in both existence and necessity, yet some further attribute supervenes upon them, that attribute must be either internal to them, external to them, or neither internal nor external.
If it is internal, it would have to follow necessarily from the presence of its cause—yet by hypothesis it is merely accidental, which is a contradiction.
If it is external, the Necessary Existent would be in need of something outside itself, and that is impossible.
If it is neither internal nor external, its cause could have no real standing, and so the attribute itself could not exist.
Thus, on the assumption that they are both Necessary Existents (1), the impossibilities just listed would ensue; but impossibilities do not in fact ensue, so the antecedent—that there are two Necessary Existents (2)—is false. Hence, there cannot be two Necessary Existents.
He answered: Praise be to Allah, Lord of the worlds. In reality, the “oneness” of the philosophers amounts to a denial of the Necessary Existent, for they affirm a Necessary Existent while rejecting its necessary concomitants. Yet to deny the concomitants is to deny that of which they are concomitants. The proofs they advance for their version of oneness are sophistical, not demonstrative. What they really intend, in what they claim is the negation of composition and plurality within the very notion of the Necessary Existent, is nothing other than the abolition of its attributes and realities—an abolition that necessarily entails nullifying the very essence of the Necessary Existent—though they themselves are unaware of the contradiction and baselessness of their words.
We shall now address the argument cited in the question—there is no power and no strength except through Allah.
They say: “If there were two Necessary Existents, then either one of them would differ from the other or it would not. If they do differ, then either what they share is a necessary concomitant of the point on which they differ, or the reverse, or what they share is an accident of their difference, or the reverse.”