There are many things that cause hardness of heart, from them:

1. Speaking too much
2. Breaking oaths and agreements
3. Laughing too much
4. Eating too much
5. Sinning too much

As for its cures, there are many, from them:

1. Remembering Allah frequently
2. Showing compassion to orphans and to the poor
3. Visiting the graveyard
4. Remembering death, the destroyer of all pleasures
5. Looking at the abode of those that were destroyed and pondering over the dwellings of those that are long gone.
6. Eating Halal

Ibn Rajab said in verse what means:

Is it a condemned building you still seek to build?
Yet that which will last, you have not constructed?

Days have passed, leaving you no excuse,
You have been warned, yet this you’ve not heeded.

You are called upon to depart at every second,
an announcement that you are the intended.

You hear this and yet you still play around,
as if your ears were deaf to that which was beckoned.

You know that ahead of you is a long, long journey
yet you have taken to it ill-equipped and unprepared.

You sleep, yet time does not, racing
behind you, so how then have you slumbered?

The deficiencies of this world are abundant
yet the love of them has you restricted.

Passing your life in play and frolic,
if you had sense no amusement upon would you’ve acted

Nothing waits after death but the fires of Hell,
or the bliss of paradise, if only you’d have obeyed

No hope shall you have to return to this world
and work deeds of righteousness or leave more equipped.

The first that I blame on this day is I;
for I have done on my own that you’ve acted

Do tell, O you who gathers up wealth
Will death be stopped by that which you’ve gathered?

Make no mistake; time is but a sword in hand
If you secure it not, with it you’ll be severed.

Days whither away every soft, subtle branch,
And the flowers of your joy are all wilted

Life is but a dream, a fleeting passing trance
You’d do well for yourself if you’ve awakened

How does it stop you from gaining the eternal?
Is it the temporary, its beauties you’ve selected?

She is lowly, even if she makes you happy a time,
Then double from her is that you’ve detested.

After passing a man is but a fleeting remark,
So do well in what’s left so in good you are mentioned.

Abridged from the book “Dhamm Qaswat Al-Qalb” by Al-Hafiz Ibn Rajab Al Hanbali, Pp.259-270, found in Majmu’ Rasa’il Al-Hafiz Ibn Rajab Al Hanbali, Dar Al Farouq Al Hadithah, Shobra, 2003.