And that the foolish among us used to utter against Allah that which was an enormity in falsehood.
Mujahid, `Ikrimah, Qatadah and As-Suddi, all said,
سَفِيهُنَا
(the foolish among us),
"They were referring to Iblis."
...
شَطَطًا
that which was an enormity in falsehood.
As-Suddi reported from Abu Malik that he said,
"This means a transgression."
Ibn Zayd said, "A great injustice."
The foolish (Safih) also carries the meaning of everyone in the category who claims that Allah has a spouse or a son. This is why Allah says here,
وَأَنَّهُ كَانَ يَقُولُ سَفِيهُنَا
(And that the foolish among us used to utter) meaning, before his acceptance of Islam.
عَلَى اللَّهِ شَطَطًا
(against Allah that which was an enormity in falsehood.) meaning, falsehood and a lie.
Thus, Allah says,
وَأَنَّا ظَنَنَّا أَن لَّن تَقُولَ الاْأِنسُ وَالْجِنُّ عَلَى اللَّهِ كَذِبًا