But the LORD said to Samuel, “Do not look on his appearance or on the height of his stature, because I have rejected him. For the LORD sees not as man sees: man looks on the outward appearance, but the LORD looks on the heart.”
Keep your heart with all vigilance, for from it flow the springs of life.
But what comes out of the mouth proceeds from the heart, and this defiles a person. For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander.
Oh, let the evil of the wicked come to an end, and may you establish the righteous - you who test the minds and hearts, O righteous God! (ESV)