What is the significance of "ve'Dal Lo Sehdar be'Rivo"?
Rashi, Targum Onkelos and Targum Yonasan: One is not allowed to honor a poor man
by judging him favorably on the basis of the fact that he is poor and needs help.
Whom one knows to be liable (Targum Yonasan).
Because it is forbidden to display pity in judgment (Targum Onkelos and Targum Yonasan), as the Torah writes in Vayikra, 19:15 (Rashbam).
Seeing as the Pasuk in Kedoshim, Vayikra (19:15) prohibits favoring a poor man, why does the Torah see fit to insert this Pasuk?
Mechilta: Because the Pasuk there refers to favoring a poor man and honoring a rich one, the Pasuk here is teaching that the reverse is also applicable.