הֵ֣ן לְרִ֤יב וּמַצָּה֙ תָּצ֔וּמוּ וּלְהַכּ֖וֹת בְּאֶגְרֹ֣ף רֶ֑שַׁע לֹא־תָצ֣וּמוּ כַיּ֔וֹם לְהַשְׁמִ֥יעַ בַּמָּר֖וֹם קוֹלְכֶֽם׃
Behold, ye fast for strife and contention, And to smite with the fist of wickedness; Ye fast not this day So as to make your voice to be heard on high.
Read halakhic rulings (Jewish law) on Isaiah 58:4: and classical halakhic sources.