וְגַם־עַתָּה֙ נְאֻם־יְהוָ֔ה שֻׁ֥בוּ עָדַ֖י בְּכָל־לְבַבְכֶ֑ם וּבְצ֥וֹם וּבְבְכִ֖י וּבְמִסְפֵּֽד׃
Yet even now, saith the LORD, Turn ye unto Me with all your heart, And with fasting, and with weeping, and with lamentation;
Read midrashic interpretation of Joel 2:12: and classical rabbinic exegesis.