The believer does the best deeds yet is most fearful [that his deeds will not be accepted]. If he were to spend a mountain of wealth [in charity], he would not feel sure [of the reward] until he sees it. The more righteous and pious he becomes, the more he fears. But the hypocrite (munafiq) says, “There are so many people, I will be forgiven, no problem”. So he does wrong and evil deeds yet hold foolish wishes about Allah.

Al-Hasan Al-Basri Al-Dhahabi, Siyar A’lam Al-Nubala 4:586