'With All Your Heart' in the Bible

And Samuel spoke to all the house of Israel saying, If you return to Jehovah with all your hearts, then put away the strange gods and Ashtaroth from among you, and prepare your hearts to Jehovah, and serve Him only. And He will deliver you out of the hand of the Philistines.

And Samuel said to the people, Do not fear. You have done all this wickedness. Yet do not turn aside from following Jehovah, but serve Jehovah with all your heart.

Only fear Jehovah, and serve Him in truth with all your heart. For consider what great things He has done for you.