This double negative is used for emphasis. It can be expressed in a positive way. Alternate translation: "Always judge rightly" (See: [[rc://en/ta/man/translate/figs-litotes]])
The words "poor" and "important" are two extremes, which together mean "anyone." You can translate this to clarify the terms. Alternate translation: "You must not show favoritism to anyone based on how much money they have" (See: [[rc://en/ta/man/translate/figs-merism]])