Brachos 18a #1: One may not walk through a cemetery (within four Amos of a Mes) with Tefilin on his head, or learning from a Sefer Torah [or reciting Shema - Sotah 43b. He mocks the dead, who cannot do Mitzvos.]

Brachos 18a #2: One who sees a Mes [being taken to burial] must accompany it (at least four Amos).

Menachos 41a: When one dies, we put Tzitzis on the shrouds, to avoid mocking him (that he is exempt from Mitzvos).

R. Yonah: One who mocks and disgraces the poor, he shows that he thinks that the Oni's poverty came from his lack of Da'as and diligence; his own wealth is due to his strength. Therefore, "Cheref Osehu."

Orchos Tzadikim (Sha'ar ha'Shetikah): One who mocks an Oni because he is poor, and he attributes this to the Oni's lack of Chachmah. He thinks that he is rich due to his Chachmah -"Kochi v'Otzen Yadi Asah Li Es ha'Chayil ha'Zeh" (Devarim 8:17). He reviles Hashem, for Hashem made him poor - "Ashir va'Rash Nifgashu Ose Kulam Hashem" (22:2). He mocks Hashem's deed!

Malbim: I already explained regarding "Oshek Dal Cheref Osehu" (14:31) that the One who made the Oni, surely He prepared his income! One who is Oshek the poor (does not pay him his wage), he reviles his Maker, as if He created him for naught. Here it adds that also one who mocks the Rash because he is weak, and he has no income, Cheref Osehu. Surely Hashem had a good intent [to make him like this]! Nothing about His creations is left to chance.

R. Yonah: His heart is Mezid. However, this is not as severe as "Cheref Osehu."

Malbim: Some come in the way of mockery, and some come in the way of vengeance, because he hates him. It says about the former "Cheref Osehu." "Some'ach l'Eid", in the way of vengeance, will not be cleansed (exempted) from punishment - "bi'Nfol Oyvecha Al Tismach