It's found here

The heart is deceptive. It wants. It covets. It lies. It clouds reality. It says, "I want, I need, I demand, I deserve" and even without the gift of true love to someone else we create friction based on lies.
Plot good not evil and reap the benefits of mercy, love and peace. 

Love intentionally. There is freedom and happiness found here.  His mercy is new every mourning.

Jeremiah 17:9

 ⁹ The heart is deceitful above all things and beyond cure. Who can understand it?

Proverbs 12:20

 ²⁰ There is deceit in the hearts of those who plot evil, but joy for those who promote peace.