Etymology

The triliteral root sīn fā hā (س ف ه) according to corpus.quran.com, occurs in the Quran 11 times.

Compare with English «stop» - "to cause (something) to cease moving or progressing".

Compare with English «stupid» - "a stupid person; a fool".

Compare with English «stuff» - "to equip, furnish".

Compare with German «stopfen» - "to stuff, to plug".

Combine with basic material Delicate, the root ṣād fā ḥā (ص ف ح), according to corpus.quran.com is used 8 times.

In the Quran

(2:130) Who would abandon the creed of Abraham except one who stops (Arab. سَفِهَ, safiha) his psychic (development)? We have staffed him in this world, and in the Hereafter, he is of the reformers.

(2:142) The stupid (Arab. السُّفَهَاءُ, l-sufahāu) from amongst the people will say: "What has turned them away from the paradigm that they were on?" Say: "To Allah belongs the east and the west. He guides whomsoever He wishes to a straight path."