ولا متبعض ولا متجزئ
He is neither part-bearing nor divisible into components.
Division into parts means that a whole consists of distinguishable components. A physical whole depends, in its present configuration, on the arrangement and relation of those components.
A table illustrates this dependence: remove a leg or the tabletop and that arrangement no longer remains. To describe God as part-bearing would introduce a kind of composition and dependence incompatible with the meaning of necessary, self-subsistent existence.
The claim is not merely that no observer has seen divine parts. It is the principled rejection of component dependence in the necessary being.