Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions. It is forbidden to say "Ya Rasul Allah" "O Allah's Messenger" ...
The hard and merciless heart is that which contains a mixture of harshness and toughness; a heart that is void of submission and the sense of turning to Allah the Exalted in repentance at all times.