The Islamic way to find righteousness

I wrote this initially for another Islamic discussion board. I have liked it so much that I have come to think it needs to be posted here, too:

The true Divine doctrines are obvious. They are openly and clearly declared in the Qur'an and in the authentic Sunnah. From the Islamic viewpoint, everything that does not obviously spring from the Qur'an and the authentic Sunnah is debatable and arguable.

I am now citing you a hadith narrated by Ahmad ibn Hanbal and Darimi and declared authentic by them. It's also found in the great forty-ahaadeeth collection of Imam Muhyid-deen an Nawawi. Listen to the Prophet of Allah (peace be upon him) give good advice to you:

Waabisah bin Ma'bad tells:

I went to the Messenger of Allah (peace and blessings of Allah be upon him). The Messenger of Allah asked me: "Have you come here to ask about righteousness?"

I said, "Messenger of Allah, yes."

Upon this, the Messenger of Allah spoke:

"Consult with your own heart (i.e. your own conscience and mind). Righteousness is what the heart is content with. And sin is what makes yourself discontent and your heart hesitant, even if all people say that that thing is good."

Do you see, my brothers and sisters? The Prophet tells us to trust our own conscience and heart as well as the conscience and hearts of other individual believers. Stop trying to dictate other Muslims what they must very exactly believe. Both you and other religious Muslims have great conscience sufficient to provide good advice to you and them all the time, always based on the clear guidance of the Qur'an and the authentic Sunnah, and nothing else.

Auzubillahi minash shaitan ir rajeem,

Bismillah ir rehman ir rahim,

Assalamualaikum wa rahmatullah wa barkatuhu,

What if someone's heart is all black with sin and corruption? When it does not recognise the good as good and bad as bad, will you still prescribe this hadith to that person ?

The prophet(saw) also said there is a peice of flesh in the body, when that is healthy whole body is healthy, and when it is diseased, the entire body is diseased, and this is the heart.

Maa Salaama,

Assalamualaikum
                   sometimes one person can listen to a song and music and will feel nothing happening to his heart. another person will listen to the same song and will feel the "zulmat" spreading in his heart or something going wrong with his heart. so whose heart is better in deciding the righteous thing.
When asked, the one who feels the "zulmat" will definitely say that music and songs are rightly forbidden while the one who doesnt feel a thing may come out and say that its a controversial question(or something similar)
the ulema say that the heart which is white (i.e has been made white through tazkia of nafs) will feel the black spots of sin while the heart which is already black with too many sins will not feel another sin.

Allah Knows Best.