Abu Bakr ibn Furak said:
“He—glorified be He—is One in His Essence, having no (1) counterpart; One in His attributes, having no peer; and One in His acts, having no partner.”
The commentator on al-Irshad, Abu al-Qasim al-Ansari, the teacher of al-Shahrastani, said:
“It is related from the Ustadh Abu Ishaq that he said: al-wahid (the One) is that which admits neither elevation nor lowering—that is, neither separation nor conjunction. He was alluding (2) to the unity of the Deity, for a substance (jawhar) is one in the sense that it is indivisible, yet it still admits delimitation, whereas the Deity—exalted is He—is truly One, admitting neither separation nor conjunction. We have already established, in the discussion on the negation of corporeality, proofs for denying partitions, and we have established proofs for denying any likeness; what remains is to establish proof for denying any partner.”
I say:
As for denying any likeness to Allah and denying any partner, this is established by the Quran, the Sunnah, and the consensus of the Salaf of this Ummah. Yet certain groups among the dialecticians introduce into this issue notions that are not indicated by the Quran and the Sunnah; indeed, those two sources negate them. Regarding the meaning they associate with the negation of divisibility, their view entails that nothing among created things could ever be called one except the indivisible atom. According to some of them, (3) even the indivisible atom may not be so described; moreover, Abu al-Maʿali was among those who doubted the very existence of the indivisible atom. Hence (4) it would follow that nothing in existence could rightly be called one. This is contrary to the Quran, the Sunnah, the consensus of the Salaf and the Imams of the Ummah, and the consensus of linguists and people of sound reason; and when (5)