Give someone a hand

Definition: To help someone with something.



Example: When my wife came home from the market I gave her a hand bring in the groceries.
 

Bite one's tongue

Definition: To hold back from saying something to or about someone else that you would like to say.


Example: When John took all of the credit for your hard work at the meeting yesterday, I had to bite my tongue or eles I would have told everyone he was a liar.

Nip something in the bud

Definition: to put a stop to something quickly before it has a chance to get worse.

Example:  John is starting to expect his wife to do everything for him.  She had better nip that in the bud before it becomes a habit.