SHAFAQNA – It is narrated from Imam Ali (AS) who said: Allah (SWT) looks kindly to the pure (clean) hearts of the servants of God . What is a pure heart? At the time of creation of the heart, God made it the place of Divine Kindness. Anything else apart from God enters the heart, the heart becomes impure.
Any evil act which the worst of them is the love of the world, effects it (the heart). It is narrated from the Prophet of Islam (PBUH) who said: The heart which has the love of anything else apart from Divine Love; will not be looked at by God . Worldly Attachments cause the heart of the human being which is the noblest of the dimensions of the existence and the place of Divine Look and maybe the place of God, cease to be a pure place.
Then The Prophet (PBUH) added: The one whose heart is pure, God will look at his/her heart, meaning that heart will become the place of Divine Look and this luminosity will enable the heart to look at the kingdom of the world and listen to whatever it is said from there.
This way the eyes and the ears of the heart will open and will see the ones whom no one else can see and can witness the unseen world. The human being should know that the worldly attachments will cause the spiritual cases to cease and the worst case is, not to be seen by God .
 Qorarul Hekam, Page 67, Hadith 906.
 Beharul Anwaar, Vol. 51, Page 258.
 The Website of Ayatollah Sheikh Mojtaba Tehrani.