Kill somebody/something with kindness
Definition 1 of 1
Pro Tip 1/3Not Literal
The phrase is figurative, meaning you 'kill' negativity or unkindness with your excessive goodness. 
Even when they spread rumors, she would just kill them with kindness.
Pro Tip 2/3Positive Tactic
It's used as a strategy to disarm someone's hostility without being aggressive. 
He was yelling, but I just smiled and offered help — kill them with kindness, right?
Pro Tip 3/3Subtle Power
The phrase suggests a subtle strength in being kind in the face of rudeness or hostility. 
Everyone was losing their patience, but she decided to kill the tension with kindness.