Rashi on Exodus 23:3/רש"י על שמות כ״ג:ג׳

1לא תהדר NEITHER SHALT THOU COUNTENANCE [THE INDIGENT IN HIS QUARREL] — You shall not pay regard to him by finding in his favour in the law suit, saying, “He is a poor man; I will find in his favour, and thus show him some measure of respect.”