Tariq bin Shihab (may Allah have mercy on him) narrated that he went to spend the night with Salman (may Allah be pleased with him) to see how much effort he put into worship. He got up to pray in the last part of the night, but it was as though he did not see what he had expected. When he mentioned this to Salman (may Allah be pleased with him), he said: "Guard these five prayers, for they are an expiation for these wounds (sins) as long as no fatal sin is committed. When the people have prayed Isha, they return in one of three states: among them are those who bear sin and have no reward, those who have reward and bear no sin, and those who have neither reward nor sin. The one who bears sin and has no reward is the man who takes advantage of the darkness of the night and the heedlessness of the people and runs headlong into disobedience. The one who has reward and bears no sin is the man who takes advantage of the darkness of the night and the heedlessness of the people and stands up to pray. And the one who has neither reward nor sin is the man who prays and then sleeps. And beware of excessive, exhausting strain (in worship); hold fast to moderation and constancy."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6026