Sticks and stones may break your bones, but harsh words never hurt you.

How many times have you heard this?  Repetition does not make something true!  Hurt feelings can take longer to heal than physical injuries.

So
be careful what you say lest you
cut someone to the quick.
The quick here is the living tissue around finger- and toe-nails.

Try not to put your foot in it.
There is a lovely expression about tactlessness.
“Every time he opens his mouth, he puts his foot in it.”  He must be a contortionist!

Here are some expressions used in arguments.

There’s a world of difference.

That’s beyond reason.

I don’t take kindly to that
means “I don’t like what you said”.

That takes the biscuit and
that puts the tin lid on it
indicate surprise and often disbelief.

Seeing that you’ve mentioned it
is the introduction to a complaint, which might not otherwise have been made.

When someone is angry or “worked up” about something they might be told to calm down.

Don’t get hot under the collar.
Anger often makes for a hot neck.  Even someone who is not wearing a shirt or blouse with a collar can be given this warning!

Don’t get airiated.
This has the same meaning, but I have been unable to find the word in a dictionary.  I have tried various spellings.  Can anyone help?

Keep your hair on.
The imagery here defeats me!  Is it a wig or a toupé?

She blew her top.
I have visions of a steam train or a safety valve.

She flew off the handle.
There is another expression about keeping a handle on something.  By losing her temper, she failed to do this.

Bury the hatchet.
A hatchet is another word for an axe.  If a quarrel or even a feud might have led to violence, this advice seems appropriate.  For a less serious difference of opinion it might be meant as a light-hearted remark.  Either way it has found its way into the vernacular.  According to Brewer in the Dictionary of Phrase and Fable, it originated with the American Indians.

They patched things up (after a quarrel).
Quarrels can do a lot of damage to a relationship unless both sides can apologise afterwards.

St Paul wrote to the Ephesians Chapter 4 verse 26 (NIV) “In your anger do not sin”;  Do not let the sun go down while you are still angry.

He was quoting David in Psalm 4 verse 4 (NIV) In your anger do not sin; when you are on your beds, search your hearts and be silent.