What do we learn from "Sifsei Chachamim Yezaru Da'as"?
Rashi: They crown Da'as. "Yezaru" is like "Zer Zahav" (Shemos 25:11).
R. Yonah: Yezaru is winnowing, like "Asher Zoreh va'Rachas uva'Mizreh" (Yeshayah 30:24), "Hine Hu Zoreh Es Goren ha'Se'orim" (Rus 3:2). Also their words [of the lips] without prior intent, there is no crookedness or mistake in them. They winnow Da'as, without crooked matters mixed in. This is like one winnows grain with a pitchfork, to separate the chaff from it.
Malbim: Chachamim put a crown around Da'as, to guard it from Kesilim, whose mouths say Iveles and doubts - "Chachamim Yitzpenu Da'as" (10:14), like I explained above.
Why does it say "Lo Chen"?
Rashi: It is not Emes.
R. Yonah: A Kesil did not accustom his Nefesh to recognize the path of Emes. His heart will not clarify Da'as from Sheker via investigation; Chachamim achieved this via habit.
Malbim: Even though Kesilim's mouths and lips say Iveles, the opposite of Da'as - "Lech mi'Neged l'Ish Kesil u'Val Yadata Sifsei Da'as" (14:7), their hearts are not so. Their hearts know the laws of Chachmah, just their desire blinds their eyes, and their hearts do not stand on a base. They move like froth on water. (10:14), like I explained above.