Rashi: Mislahamim are l'Mahalumos (severe blows).

R. Yonah: Nirgan is a complainer. He constantly complains about his friends, and catches them in their words and deeds. He judges that they intended to disgrace him and harm him. He complains about them. This is like "va'Teragnu v'Ohaleichem" (Devarim 1:27). They appear as if they are insulted, pursued and stricken.

Malbim: Nirgan constantly complains that Hashem made him for his evil, and that there are more evils in the world than good things. It would have been better that he not be created! So he constantly complains about Hashem's conduct, that He abandoned him to chance. His words are k'Mislahamim - as if Hashem constantly strikes him and does evil to him.

R. Yonah: The complaints of a Nirgan reach to the Nefesh. When his friend is careful with all his heart to be careful not to damage or disgrace him, he blames them groundlessly and says that they sinned. Sometimes his friend intended to benefit him and honor him, but he judges it oppositely in his deeds and words! This is like "Meshiv Ra'ah Tachas Tovah" (17:13).

Malbim: These evils and blows [about which he complains] are not external to him. Rather, they are in his innards and thoughts. In his imagination, he constantly worries and complains and pictures that whatever someone else has, he lacks it, and all Hashem's good deeds are bad, This is like the Mashal of the blind people that Chovos ha'Levavos brings ¹ , and like Moreh ha'Nevuchim explains "Asah ha'Elokim Es ha'Adam Yashar [v'Hemah Vikshu Chishbonos Rabim]" (Koheles 7:29). The source of the evils is in himself and his imagination. His words themselves strike him, and not external blows. If he will not complain, he will find just the contrary, that everything is for good; all is Chesed and Brachah, and he will rejoice in his portion and his Nefesh will delight in Hashem's salvation. Hashem created man straight, and prepared everything for his benefit!