Answer
To obtain a pure heart, adhere to the following advise of Hadhrat Umar (Radhiallaahu Anhu): At first to the rememberance of Allah Ta’ala, because it is a cure; and abstain from speaking about people (backbiting, slandering, etc.) because it is a sickness.
It has been narrated from Rasulullah (Sallallaahu Alayhi Wasallam) that the heart get rusted as iron gets rust. The Sahaaba (Radhiallaahu Anhum) asked, ?What could cleanse the heart, then?? Rasulullah (Sallallaahu Alayhi Wasallam) replied, ?Frequent recitation of the Qur’aan and Dhikr (rememberance) of Allah.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai