On the authority of an-Nawwas ibn Samaan (Radhi-Allahu ‘anhu) that the Messenger of Allah (salAllahu alayhi wa sallam) said:
Righteousness is good morality, and wrongdoing is that which wavers in your heart and which you dislike people finding out about.
[ It was related by Muslim ]
On the authority of Wabisa ibn Mabad (Radhi-Allahu ‘anhu) who said: I came to the Messenger of Allah (salAllahu alayhi wa sallam) and he said: “You have come to ask about righteousness?”
I said: “Yes.”
He (salAllahu alayhi wa sallam) said: “Consult your heart. Righteousness is that about which the soul feels tranquil and the heart feels tranquil, and wrongdoing is that which wavers in the soul and moves to and fro in the breast even though people again and again have given you their legal opinion [in its favor].”
[ A Hasan (fair) Hadith transmitted from the two Imams, Ahmad ibn Hanbal and ad-Darimi, with a Hasan (fair) chain of authority ]