“‘Now, therefore,’ says the LORD, ‘turn to Me with all your heart’… rend your heart, and not your garments” (Joel 2:12-13).
The rending (tearing) of garments was a common practice among people in the Bible lands. It was done in times of sorrow, or distress (Genesis 37:29; 2 Samuel 13:19; Ezra 9:3, 5; Jeremiah 36:24). It was done in anger or shock (Matthew 26:65; Mark 14:63).
However, some evidently abused this practice. They made an outward show of emotion, but their hearts were not in it.
God wanted more than an outward show of repentance. He wanted them to truly repent in their hearts. He told them to rend their hearts, and not their garments (only, alone B.H.). He wanted their hearts (cf. Deuteronomy 4:29; 6:4-6; 10:12-13; 11:13-15; 30:9-10).
He still wants the heart. He wants it in our belief. “For with the heart one believes unto righteousness” (Romans 10:10). He wants it in our repentance. “For godly sorrow produces repentance leading to salvation” (2 Corinthians 7:10 cf. Acts 2:37). He wants it in our obedience. Paul wrote to the saints in Rome, who had “obeyed from the heart” the form of doctrine (Romans 6:17). He wants it in our service. Paul wrote, “God is my witness, whom I serve with my spirit” (Romans 1:9). He wants it in our worship. Our singing is to be with grace in our hearts to the Lord (Colossians 3:16). Our giving is to be done cheerfully (2 Corinthians 9:7). Consider the words of the Psalms (Psalms 9:1; 111:1; 119:2, 10, 34, 69; 138:1). He wants it in our love. Jesus taught, “You shall love the LORD your God with all your heart, with all your soul, and with all your mind” (Matthew 22:37 cf. Deuteronomy 6:5). He has never been pleased with those draw near with their mouths and honor Him with their lips, but have hearts for from Him (Matthew 15:8 cf. Isaiah 29:13).