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.