The heart is…

Blessed is the man that trusteth in the Lord , and whose hope the Lord is. For he shall be as a tree planted by the waters, and that spreadeth out her roots by the river, and shall not see when heat cometh, but her leaf shall be green; and shall not be careful in the year of drought, neither shall cease from yielding fruit. The heart is deceitful above all things, and desperately wicked: who can know it? Jeremiah 17:7‭-‬9 KJV https://bible.com/bible/1/jer.17.7-9.KJV

With all your heart.

“For I know the thoughts that I think toward you, saith the Lord, thoughts of peace, and not of evil, to give you an expected end. Then shall ye call upon me, and ye shall go and pray unto me, and I will hearken unto you. And ye shall seek me, and find me, when ye shall search for me with all your heart.”
‭‭Jeremiah‬ ‭29:11-13‬ ‭KJV‬‬