Reported by Wabisah bin Ma’bad (RA): I went to the Messenger of Allah (sas) and he asked me “Have you come to inquire about piety?” I replied in the affirmative. Then he said, “Ask your heart regarding it. Piety is that which contents the soul and comforts the heart, and sin is that which causes doubts and disturbs the heart, even if people pronounce it lawful and give you verdicts on such matters again & again.
[Ahmad & Ad-darmi]
A lot of times, we will realise that our minds and hearts are not in harmony regarding certain decisions we take or actions we do. Our minds (brain) create many reasons why such an action/decision is the right thing to do and persuades the heart to agree, but we find out that the heart only partially agrees, and we are left with a shadow of doubt in our hearts, even though we might try to fight it.
We should learn to listen to our hearts all the time, for indeed, that’s where piety resides.