On the authority of an-Nawas bin Sam’an (may Allah be pleased with him), that the Prophet ﷺ said:

Righteousness is in good character, and wrongdoing is that which wavers in your soul, and which you dislike people finding out about.

[Muslim]
And on the authority of Wabisah bin Ma’bad (may Allah be pleased with him) who said:

I came to the Messenger of Allah ﷺ and he ﷺ said, “You have come to ask about righteousness.” I said, “Yes.” He ﷺ said, “Consult your heart. Righteousness is that about which the soul feels at ease and the heart feels tranquil. And wrongdoing is that which wavers in the soul and causes uneasiness in the breast, even though people have repeatedly given their legal opinion [in its favour].”

A good hadeeth transmitted from the musnads of the two imams, Ahmed bin Hambal and Al- Darimi, with a good chain of authorities.

عَنْ النَّوَّاسِ بْنِ سَمْعَانَ رَضِيَ اللهُ عَنْهُ عَنْ النَّبِيِّ ﷺ قَالَ: "الْبِرُّ حُسْنُ الْخُلُقِ، وَالْإِثْمُ مَا حَاكَ فِي صَدْرِك، وَكَرِهْت أَنْ يَطَّلِعَ عَلَيْهِ النَّاسُ" رَوَاهُ مُسْلِمٌ [رَوَاهُ مُسْلِمٌ]. وَعَنْ وَابِصَةَ بْنِ مَعْبَدٍ رَضِيَ اللهُ عَنْهُ قَالَ: أَتَيْت رَسُولَ اللَّهِ ﷺ فَقَالَ: "جِئْتَ تَسْأَلُ عَنْ الْبِرِّ؟ قُلْت: نَعَمْ. فقَالَ: استفت قلبك، الْبِرُّ مَا اطْمَأَنَّتْ إلَيْهِ النَّفْسُ، وَاطْمَأَنَّ إلَيْهِ الْقَلْبُ، وَالْإِثْمُ مَا حَاكَ فِي النَّفْسِ وَتَرَدَّدَ فِي الصَّدْرِ، وَإِنْ أَفْتَاك النَّاسُ وَأَفْتَوْك" .
حَدِيثٌ حَسَنٌ، رَوَيْنَاهُ في مُسْنَدَي الْإِمَامَيْنِ أَحْمَدَ بْنِ حَنْبَلٍ [رقم:4/227]، وَالدَّارِمِيّ [2/246] بِإِسْنَادٍ حَسَنٍ.