What does the Bible say about rending hearts?

In Joel 2:12-14, God calls His people to turn to Him with all their hearts and to rend their hearts instead of merely tearing their garments. This is a call to genuine repentance that goes beyond outward actions. True repentance involves a heart change where one acknowledges their sinfulness and seeks God's grace. The emphasis is on the internal transformation instead of external signs of sorrow. Warnings of judgment can lead to moral reformation, but only a heart transformed by God can result in true change and reconciliation with Him.