harden your heart against somebody/something

harden (one's) heart against (someone or something)

1. To stop feeling kindness and compassion toward someone or something. Don't harden your heart against people who need our help. It's not their fault they're in that situation.
2. To cause one to stop feeling kindness and compassion toward someone or something. I worry that all the trauma she's already been through at such a young age will harden her heart against other people.
See also: harden, heart
Farlex Dictionary of Idioms.

ˌharden your ˈheart against somebody/something

no longer be emotionally affected by somebody/something because you feel angry, bitter, etc., towards them/it: Doctors have to harden their hearts against the suffering they see every day.
See also: harden, heart, somebody, something
Farlex Partner Idioms Dictionary
See also:
  • harden (one's) heart against (someone or something)
  • harden one's heart
  • harden your heart
  • harden
  • harden (one's) heart
  • steel (one's) heart against (someone or something)
  • steel one's heart against
  • take pity
  • take pity on
  • take pity on (someone or something)