'With All Your Heart' in the Bible

Samuel spoke to all the house of Israel, saying, "If you do return to the LORD with all your heart, then put away the foreign gods and the Ashtaroth from among you, and direct your hearts to the LORD, and serve him only; and he will deliver you out of the hand of the Philistines."

Samuel said to the people, "Do not be afraid. You have indeed done all this evil; yet do not turn aside from following the LORD, but serve the LORD with all your heart.

Only fear the LORD, and serve him in truth with all your heart; for consider how great things he has done for you.