كتاب الإيمان
1  
The Book of Faith
(59)
Chapter: If a person thinks of doing a good deed it will be recorded for him, and if he thinks of doing a bad deed it will not be recorded for him
(59)
باب إِذَا هَمَّ الْعَبْدُ بِحَسَنَةٍ كُتِبَتْ وَإِذَا هَمَّ بِسَيِّئَةٍ لَمْ تُكْتَبْ ‏‏
Sahih Muslim 131 a

It is narrated on the authority of Ibn Abbas that the Messenger of Allah (ﷺ) transmitted it from the Blessed and Great Lord:

Verily Allah recorded the good and the evil and then made it clear that he who intended good but did not do it, Allah recorded one complete good in his favour, but if he intended it and also did it, the Glorious and Great Allah recorded ten to seven hundred virtues and even more to his credit. But it he intended evil, but did not commit it, Allah wrote down full one good in his favour. If he intended that and also committed it, Allah made an entry of one evil against him.
حَدَّثَنَا شَيْبَانُ بْنُ فَرُّوخَ، حَدَّثَنَا عَبْدُ الْوَارِثِ، عَنِ الْجَعْدِ أَبِي عُثْمَانَ، حَدَّثَنَا أَبُو رَجَاءٍ الْعُطَارِدِيُّ، عَنِ ابْنِ عَبَّاسٍ، عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم فِيمَا يَرْوِي عَنْ رَبِّهِ تَبَارَكَ وَتَعَالَى قَالَ ‏ "‏ إِنَّ اللَّهَ كَتَبَ الْحَسَنَاتِ وَالسَّيِّئَاتِ ثُمَّ بَيَّنَ ذَلِكَ فَمَنْ هَمَّ بِحَسَنَةٍ فَلَمْ يَعْمَلْهَا كَتَبَهَا اللَّهُ عِنْدَهُ حَسَنَةً كَامِلَةً وَإِنْ هَمَّ بِهَا فَعَمِلَهَا كَتَبَهَا اللَّهُ عَزَّ وَجَلَّ عِنْدَهُ عَشْرَ حَسَنَاتٍ إِلَى سَبْعِمِائَةِ ضِعْفٍ إِلَى أَضْعَافٍ كَثِيرَةٍ وَإِنْ هَمَّ بِسَيِّئَةٍ فَلَمْ يَعْمَلْهَا كَتَبَهَا اللَّهُ عِنْدَهُ حَسَنَةً كَامِلَةً وَإِنْ هَمَّ بِهَا فَعَمِلَهَا كَتَبَهَا اللَّهُ سَيِّئَةً وَاحِدَةً ‏"‏ ‏.‏
Reference : Sahih Muslim 131a
In-book reference : Book 1, Hadith 245
USC-MSA web (English) reference : Book 1, Hadith 237
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