This composition entails the need for parts - something that...
Why should it be inadmissible to suppose two simple entities (huwiyyatân) of unknown nature that differ from one another with all their quiddities, while each of them is a self-existing necessary being, so that the concept of existential necessity be abstracted from each of them in an accidental manner? The answer to this is that it is inadmissible because it involves the abstraction of a single concept from different entities qua different entities.
Moreover, this line of reasoning ascribes quiddity to the Necessary Being, and it was established earlier that Its quiddity is Its existence. Furthermore, it involves the derivation of existence from quiddity, whereas, as mentioned earlier, existence is fundamental (ashîl) and quiddity derived (i’tibârî), and the derivation of something fundamental from that which is derived makes no sense.
It follows from the unity of the Necessary Being - i.e., in this particular sense of unity - that Its existence is not limited by any limit of privation (hadd ‘adamî) so as to exclude anything beyond It. It also follows from it that Its essence is simple, without composition of any kind; for composition, whatever its form, does not occur without parts that make up the whole, whose actualization depends on the actualization of the parts that it needs, and need contradicts essential necessity.
الفصل الثالث في أن الواجب تعالى هو المبدأ المفيض لكل وجود و كمال وجودي ---------------------------------------------------------------------- كل موجود غيره تعالى ممكن بالذات لانحصار الوجوب بالذات فيه تعالى و كل ممكن فإن له ماهية هي التي تستوي نسبتها إلى الوجود و العدم و هي التي تحتاج في وجودها إلى علة بها يجب وجودها فتوجد و العلة إن كانت واجبة بالذات فهو و إن كانت واجبة بالغير انتهى ذلك إلى الواجب بالذات فالواجب بالذات هو الذي يفيض عنه وجود كل ذي وجود من الماهيات.