Sahih al-Bukhari 42

Arabic

حَدَّثَنَا إِسْحَاقُ بْنُ مَنْصُورٍ، قَالَ حَدَّثَنَا عَبْدُ الرَّزَّاقِ، قَالَ أَخْبَرَنَا مَعْمَرٌ، عَنْ هَمَّامٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ إِذَا أَحْسَنَ أَحَدُكُمْ إِسْلاَمَهُ، فَكُلُّ حَسَنَةٍ يَعْمَلُهَا تُكْتَبُ لَهُ بِعَشْرِ أَمْثَالِهَا إِلَى سَبْعِمِائَةِ ضِعْفٍ، وَكُلُّ سَيِّئَةٍ يَعْمَلُهَا تُكْتَبُ لَهُ بِمِثْلِهَا ‏"‏‏.‏

English translation

Narrated Abu Huraira: Allah's Messenger (ﷺ) said, "If any one of you improves (follows strictly) his Islamic religion then his good deeds will be rewarded ten times to seven hundred times for each good deed and a bad deed will be recorded as it is

Reference: Sahih al-Bukhari 42, Book of Belief. English translation by Dr. Muhammad Muhsin Khan.