(The truth is) man is the evaluator of his own self! (Remember 17:14 “Read your book [knowledge] of life! Sufficient for you is your individual consciousness at this stage to discern the consequences of your actions.”)
Al-muntakhab fi tafsir al-Qur'an al-Karim
Each one shall be his own witness, and his deeds shall be a witness of his worth. He knows exactly all that he had done and he also knows if he had perverted best things to worst abuse or to their meanest use