The heart is deceitful above all things, and desperately wicked: who can know it? I the LORD search the heart, I try the reins, even to give every man according to his ways, and according to the fruit of his doings.
(Jer 17:9-10)

He that trusteth in his own heart is a fool: but whoso walketh wisely, he shall be delivered.
(Pro 28:26)

Create in me a clean heart, O God; and renew a right spirit within me.
(Psa 51:10)