Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 277
The full Hebrew text of Mishneh Torah, Negative Mitzvot, Chapter 277, with English translation by Maimonides (Rambam).
שלא לרחם על עני בדין, שנאמר "וְדָל לֹא תֶהְדַּר בְּרִיבוֹ" (שמות כג, ג).
Not to have mercy on a poor person in judgment, as [Exodus 23:3] states: "And do not favor a poor man in his cause."