John Gill Commentary Proverbs 31:9

"Open thy mouth, judge righteously, And minister justice to the poor and needy." — Proverbs 31:9 (ASV)

Open your mouth, judge righteously
Having heard the cause, pronounce a righteous sentence; deliver it freely and impartially, with all readiness and boldness, not caring for the censures of wicked and unjust men; and plead the cause of the poor and needy ;
who are oppressed by the rich, cannot plead for themselves, nor fee others to plead for them; do you do it freely and faithfully. Thus as Lemuel's mother cautions him against women and wine, she advises him to do the duties of his office in administering impartial justice to all, and particularly in being the advocate and judge of the indigent and distressed.