Jeremiah 17:

The Sin and Punishment of Judah
…8"For he will be like a tree planted by the water, That extends its roots by a stream And will not fear when the heat comes; But its leaves will be green, And it will not be anxious in a year of drought Nor cease to yield fruit. 9"The heart is more deceitful than all else And is desperately sick; Who can understand it? 10"I, the LORD, search the heart, I test the mind, Even to give to each man according to his ways, According to the results of his deeds.…

Cross References

Matthew 13:15
For this people's heart has become calloused; they hardly hear with their ears, and they have closed their eyes. Otherwise they might see with their eyes, hear with their ears, understand with their hearts and turn, and I would heal them.'
Mark 2:17
On hearing this, Jesus said to them, "It is not the healthy who need a doctor, but the sick. I have not come to call the righteous, but sinners."