Surah 42. Ash-Shura, Ayah 16

I.e., about His attributes and the "how" of His Being, all of which is beyond the grasp of the human mind.

After He has been accepted. The disputants are the Unbelievers who pugnaciously assault the minds of Believers after the Believers have by conviction accepted Faith in Allah as leading to spiritual Light. Such disputation is futile. An inner spiritual experience can never be shaken by dialectical assaults. On the contrary such disputations recoil on the heads of those who indulge in them. Allah's Wrath is on them in this life, and the terrible Penalty of the Hereafter must inevitably follow their evil plots against Truth.