عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللّٰه صلّى اللّٰه عليه وسلّم: إِذَا أَحْسَنَ أَحَدُكُمْ إِسْلَامَهُ، فَكُلُّ حَسَنَةٍ يَعْمَلُهَا تُكْتَبُ لَهُ بِعَشْرِ أَمْثَالِهَا إِلَى سَبْعِمِائَةِ ضِعْفٍ، وَكُلُّ سَيِّئَةٍ يَعْمَلُهَا تُكْتَبُ لَهُ بِمِثْلِهَا.
Hazrat Abu Hurairahra narrated that “Allah’s Messengersa said, ‘If any one of you perfects their [practice of] Islam, every good deed they perform will be recorded for them as tenfold to seven hundred times over, and every bad deed they commit will be recorded for them as one equivalent sin.’”
(Sahih al-Bukhari, Kitab al-iman, Bab husni imani l-mar’, Hadith 42)