וְקִרְע֤וּ לְבַבְכֶם֙ וְאַל־בִּגְדֵיכֶ֔ם וְשׁ֖וּבוּ אֶל־יְהוָ֣ה אֱלֹֽהֵיכֶ֑ם כִּֽי־חַנּ֤וּן וְרַחוּם֙ ה֔וּא אֶ֤רֶךְ אַפַּ֙יִם֙ וְרַב־חֶ֔סֶד וְנִחָ֖ם עַל־הָרָעָֽה׃
And rend your heart, and not your garments, And turn unto the LORD your God; For He is gracious and compassionate, long-suffering, and abundant in mercy, And repenteth Him of the evil.
Read kabbalistic (mystical) interpretation of Joel 2:13: and classical mystical sources.