Why does it say "Gam Zos me'Im Hashem"?
Rashi: Also this, like those who thresh grain and bang Ketzach and cumin, came from Hashem.
Radak: At the beginning of the Parashah, it says "Koli" and "Imrasi" (23). Do not think that I said to you on my own. This, like other things that I tell you, are from Hashem.
Malbim: We see that existence spreads without limit - "Mah Rabu Ma'asecha Hashem" (Tehilim 104:24). Even so, we sense great wonders of His supreme Chachmah in every detail.
What is "Hifli Etzah"?
Rashi: He showed to you hints, in a new way - a wondrous metaphor. Just like Ketzach and cumin, we do not thresh them much, because they are banged easily, so if you would accept Musar quickly, Hashem would not make decrees heavy on you. You are hard, and do not accept rebuke. Therefore He is very heavy upon you, but not forever, to be eradicated. The arrows of his blows will finish, and you will not be finished. If you would be eradicated easily, he would not test you with harsh afflictions, like a flax seller. When he knows that his flax is good, he beats on it.
Malbim: Each detail of the creation has unlimited Chachmah hidden in it - "Mah Gadlu Ma'asecha Hashem" (Tehilim 92:6). Even so, "Me'od Amku Machshevosecha; Ish Ba'ar Lo Yeda" (ibid., 6-7). It is mostly hidden. Only those who see with Ru'ach Hashem see it. The Etzah is the hidden purpose in every creation. We find that preparation of bread is a Mashal for fixing the Nefesh.
