Mercy is the strongest quality of only a person with incredible strength and immense compassion.

Lord Ram  said in the Ramcharitmanas:

The conduct of the saint and the sinner is analogous to that of the sandal tree and the axe; for – mark it, brother – the axe cuts down the tree, but the fragrant sandal imparts its perfume to the very axe that fells it.

For this reason sandal finds its way to the heads of the Gods, while the axe, for its punishment, has its steel edge heated in the fire and beaten with a hammer.

A person who gives mercy because of forced circumstances or under duress can not be called truly merciful.

One who says they forgive but will not forget also cannot be called truly merciful.

People of true mercy are very rare in today’s world and even if they are found, most people who receive their mercy, mistake their kindness for weakness, and continue to remain ungrateful.

Most intelligent merciful people realise you cannot fight fire with fire.

It only makes the fire grow stronger.

Only water can put out fire.

People who are merciful are like the clean, cool, refreshing waters of a holy river.

The same water that sustains you, gives you life and that you can drink, feel, bathe and swim in.

But it must also be remembered that the same water that gives you life can also drown you.

Water is the softest of substances, but it can also destroy the hardest of rocks.

Water can destroy rocks that even the hardest steel and diamond will fail to break.

Hence the person who is granted mercy should sincerely value and appreciate the strength, and magnanimity, and more than that, the benevolence, kindness and compassion in the heart of the person who granted them mercy.

Only oppressors who realise the real priceless value of this mercy can truly reform.

A wicked person who is dipped in this refreshing water of mercy,  is cleansed of all sins if they sincerely reform.

But some fires can not be put out with water, but only by poisonous chemicals and poisonous chemical foams.

As Tulasidas said in the Ramcharitmanas:

However carefully you may bring up a crow and feed it with rice pudding, will it ever give up eating meat?

There are some people in this world whose fire can only be put out by poison.

It is for such people that Justice is dispensed through fear and retribution.