מִ֥י יוֹדֵ֖עַ יָשׁ֣וּב וְנִחָ֑ם וְהִשְׁאִ֤יר אַֽחֲרָיו֙ בְּרָכָ֔ה מִנְחָ֣ה וָנֶ֔סֶךְ לַיהוָ֖ה אֱלֹהֵיכֶֽם׃ (פ)
Who knoweth whether He will not turn and repent, And leave a blessing behind Him, Even a meal-offering and a drink-offering Unto the LORD your God?
Read halakhic rulings (Jewish law) on Joel 2:14: and classical halakhic sources.