The Conditions for a Pure Heart
There are two requirements for having a pure heart (Qalb-e-Saleem). First, it should be free of diseases. The Holy Quran has declared denial (Kufr), polytheism (Shirk) and obeying the desires of the soul (Nafs) as the diseases of the heart. The only way to get rid of these ailments is to get treated by a "spiritual doctor".
The second condition is that the Qalb (heart) must be fed its proper nourishment. Just as a proper diet makes the human body healthy and strong, proper nourishment is also essential for the health and strength of Qalb. However, the nourishment of the Qalb is different from that of the body. The righteous diet for the Qalb has been alluded to by Allah (the Greatest) as follows:
الا بِذِكْر اللهِ تَطْمئِنُّ القُلوبُ
"Unquestionably, by the remembrance of Allah hearts are assured." [13:28]
The treatment and nourishment for Qalb cannot be anywhere except with the accomplished Sufi Masters.