If a disbeliever performs a good deed, he sees its outcome in this world. On the Day of Resurrection, only regret remains for him: he will receive no reward, because his deed was not done for God. Yet he will receive the full and complete consequence of its harm.
A believer, by contrast, benefits from some of the Lord’s special graces for his good deeds until the Day of Resurrection, and receives their ultimate and greater reward on that Day. As for his wrongful deeds, he suffers on their account until the Day of Resurrection; then, on the Day of Judgment, after his misdeeds have been exposed and fully reckoned, he is forgiven. Of course, this forgiveness applies to some reprehensible deeds; the consequences of certain misdeeds may continue as suffering on the Day of Gathering. Yet in the end, he too will be encompassed by the forgiveness of the Most Merciful of the merciful.
فی تفسیر علی بن إبراهیم و فی روایه أبی الجارود عن أبی جعفر علیه السلام فی قوله: «فمن یعمل مثقال ذره خیرا یره» یقول: إن کان من أهل النار و قد کان عمل فی الدنیا مثقال ذره خیرا یره یوم القیامه حسره إنه کان عمله لغیر الله، «و من یعمل مثقال ذره شرا یره» یقول: إن کان من أهل الجنه رأى ذلک الشر یوم القیامه ثم غفر له.
Tafsīr Nūr al-Thaqalayn, vol. 5, p. 651.