Sahih Muslim 2553 b
Nawwas b. Sam'an reported:
I stayed with Allah's Messenger (ﷺ) for one year. What obstructed me to migrate was (nothing) but (persistent) inquiries from him (about Islam). (It was a common observation) that when anyone of us migrated (to Medina) he ceased to ask (too many questions) from Allah's Messenger (ﷺ). So I asked him about virtue and vice. Thereupon Allah's Messenger (ﷺ) said: Virtue is a kind disposition and vice is what rankles in your mind and that you disapprove of its being known to the people.
حَدَّثَنِي هَارُونُ بْنُ سَعِيدٍ الأَيْلِيُّ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ وَهْبٍ، حَدَّثَنِي مُعَاوِيَةُ، - يَعْنِي
 ابْنَ صَالِحٍ - عَنْ عَبْدِ الرَّحْمَنِ بْنِ جُبَيْرِ بْنِ نُفَيْرٍ، عَنْ أَبِيهِ، عَنْ نَوَّاسِ بْنِ سِمْعَانَ، قَالَ أَقَمْتُ
 مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم بِالْمَدِينَةِ سَنَةً مَا يَمْنَعُنِي مِنَ الْهِجْرَةِ إِلاَّ الْمَسْأَلَةُ كَانَ
 أَحَدُنَا إِذَا هَاجَرَ لَمْ يَسْأَلْ رَسُولَ اللَّهِ صلى الله عليه وسلم عَنْ شَىْءٍ - قَالَ - فَسَأَلْتُهُ
 عَنِ الْبِرِّ وَالإِثْمِ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏
"‏ الْبِرُّ حُسْنُ الْخُلُقِ وَالإِثْمُ مَا حَاكَ
 فِي نَفْسِكَ وَكَرِهْتَ أَنْ يَطَّلِعَ عَلَيْهِ النَّاسُ ‏"‏ ‏.‏