The soul's substance which had, in this life, a certain fluidity, is as it were fixed or crystallized when life is over; it cannot change, however much it might wish to do so. "If each soul that hath done ill possessed all that is in the earh, it would seek to ransom itslef therewith, and they feel remorseful when they see the penalty; but it has been judget between them in justice and they are not wronged." (Qur'an 10: 54)
This world is the place of mercy, where we need only ask in order to receive; on the Day, pure objectivity rules, and we are what we are or what we have made of ourselves. "Say, O My Servants who have wronged their own souls, despair not of the mercy of Allah, who forgiveth all sins. Indeed He is the Forgiving, the Merciful. And turn unto your Lord in repentance and submit to Him before there cometh unto you the penalty. Then they will not be helped." (Qur'an 39: 53-54).