What do we learn from "Cherdas Adam Yiten Mokesh"?
Rashi #1: The verse should be re-arranged. The Mokesh (stumbling block) of an Aveirah puts fear on a person.
Rashi #2: Because a person is stingy, and fears that if he gives Tzedakah, he will need [to take from] people, this fear is a stumbling block for him 1 .
R. Yonah (3:26): Fearing a person is sin. It is a snare, and strengthens the enemy and brings the affliction closer. One must fear only Hashem. When one trusts in and hopes to Hashem, the more that he fears sin, the stronger is his trust; his heart will not soften. "Mi ha'Ish ha'Yarei v'Rach ha'Levav Yelech v'Yashov l'Veiso v'Lo Yimas Es Levav Echav ki'Lvavo" (Devarim 20:8). His heart is soft because he fears the nation and their great camps. Perhaps he truly believes that everything is in Hashem's hand, but his heart is soft due to small Bitachon; his weak nature overpowers. "Mi At va'Tir'i me'Enosh Yamus" (Yeshayah 51:12). This is lowliness of the Nefesh. Fearing man is forgetting Hashem - "va'Tishkach Hashem
What do we learn from "u'Vote'ach ba'Shem Yesugav"?
R. Yonah (3:26): One who trusts in Hashem will be saved from the affliction in the reward of the Bitachon, even if the affliction should have come on him. And so says the coming verse, "Rabim Mevakshim Pnei Moshel ume'Hashem Mishpat Ish."
Malbim: Fear of panic shows that he does not trust in Hashem. One who trusts in Hashem, he is not terrified by any occurrence. He is protected, and does not fear, like Hillel said (Brachos 60a) 'I am sure that the scream I heard was not from my house' - "mi'Shemu'ah Ra'ah Lo Yira Nachon Libo Batu'ach ba'Shem" (Tehilim 112:7).