The Bible speaks a lot about our heart. The New Testament alone mentions it 149 times, the four gospels 49 times.
“Love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength” (Mark 12:30)
I expect you’re familiar with the above verse. Besides the fact the heart is mentioned first, I like the repetition of “all”:
“all your heart
all your soul
all your mind
all your strength”