Proverbs 27:19
"As in water face answereth to face, so the heart of man to man."
Cross References (ranked by relevance)
Psalm 33:15
12
He fashioneth their hearts alike; he considereth all their works.
Mark 7:21
For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders,
Genesis 6:5
And God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.