How do I differentiate between truth and injustice?

Righteousness is soundness, steadfastness, and truthfulness, and injustice is putting something in an improper place. Allah has created His servants upon righteousness, so if one's innate disposition is not corrupted, they will perceive things as they truly are, rejecting what is wrong and recognizing what is right. The truth is that righteousness, truthfulness, and justice are what came in the Book of Allah and the Sunnah of His Messenger, and that injustice, falsehood, and oppression are what Allah and His Messenger have forbidden.