talking too much without zikr causes hardness of heart

'Abdullah ibne-'Umar Radiyallahu 'anhuma narrates that 
Rasullullah Sallallahu 'alaihi wasallam said: 
Do not speak too much except in glorifying Allah, for talking too much without remembering Allah causes hardness of the heart. And amongst the people farthest away from Allah are those, whose hearts are hard.
 (Tirmidhi Hadith No 2411)