What Does the Bible Say About Fasting?

"Now in the twenty-fourth day of this month the children of Israel were assembled with fasting, with sackcloth, and dirt on them. The offspring of Israel separated themselves from all foreigners and stood and confessed their sins and the iniquities of their fathers. They stood up in their place, and read in the book of the law of the LORD their God a fourth part of the day; and a fourth part they confessed and worshiped the LORD their God. Then Jeshua, Bani, Kadmiel, Shebaniah, Bunni, Sherebiah, Bani, and Chenani of the Levites stood up on the stairs, and cried with a loud voice to the LORD their God. Then the Levites, Jeshua, and Kadmiel, Bani, Hashabneiah, Sherebiah, Hodiah, Shebaniah, and Pethahiah, said, “Stand up and bless the LORD your God from everlasting to everlasting! Blessed be your glorious name, which is exalted above all blessing and praise! You are the LORD, even you alone. You have made heaven, the heaven of heavens, with all their army, the earth and all things that are on it, the seas and all that is in them, and you preserve them all. The army of heaven worships you. You are the LORD, the God who chose Abram, brought him out of Ur of the Chaldees, gave him the name of Abraham,"

"Now when Mordecai found out all that was done, Mordecai tore his clothes and put on sackcloth with ashes, and went out into the middle of the city, and wailed loudly and bitterly. He came even before the king’s gate, for no one is allowed inside the king’s gate clothed with sackcloth. In every province, wherever the king’s commandment and his decree came, there was great mourning among the Jews, and fasting, and weeping, and wailing; and many lay in sackcloth and ashes. Esther’s maidens and her eunuchs came and told her this, and the queen was exceedingly grieved. She sent clothing to Mordecai, to replace his sackcloth, but he didn’t receive it. Then Esther called for Hathach, one of the king’s eunuchs, whom he had appointed to attend her, and commanded him to go to Mordecai, to find out what this was, and why it was. So Hathach went out to Mordecai, to the city square which was before the king’s gate. Mordecai told him of all that had happened to him, and the exact sum of the money that Haman had promised to pay to the king’s treasuries for the destruction of the Jews. He also gave him the copy of the writing of the decree that was given out in Susa to destroy them, to show it to Esther, and to declare it to her, and to urge her to go in to the king to make supplication to him, and to make request before him for her people. Hathach came and told Esther the words of Mordecai."

"but when this became known to the king, he commanded by letters that his wicked plan, which he had planned against the Jews, should return on his own head, and that he and his sons should be hanged on the gallows. Therefore they called these days “Purim”, from the word “Pur.” Therefore because of all the words of this letter, and of that which they had seen concerning this matter, and that which had come to them, the Jews established and imposed on themselves, on their descendants, and on all those who joined themselves to them, so that it should not fail that they would keep these two days according to what was written and according to its appointed time every year; and that these days should be remembered and kept throughout every generation, every family, every province, and every city; and that these days of Purim should not fail from among the Jews, nor their memory perish from their offspring. Then Esther the queen, the daughter of Abihail, and Mordecai the Jew wrote with all authority to confirm this second letter of Purim. He sent letters to all the Jews in the hundred twenty-seven provinces of the kingdom of Ahasuerus with words of peace and truth, to confirm these days of Purim in their appointed times, as Mordecai the Jew and Esther the queen had decreed, and as they had imposed upon themselves and their descendants in the matter of the fastings and their mourning."

"By David. Contend, LORD, with those who contend with me. Fight against those who fight against me. Take hold of shield and buckler, and stand up for my help. Brandish the spear and block those who pursue me. Tell my soul, “I am your salvation.” Let those who seek after my soul be disappointed and brought to dishonor. Let those who plot my ruin be turned back and confounded. Let them be as chaff before the wind, the LORD’s angel driving them on. Let their way be dark and slippery, the LORD’s angel pursuing them. For without cause they have hidden their net in a pit for me. Without cause they have dug a pit for my soul. Let destruction come on him unawares. Let his net that he has hidden catch himself. Let him fall into that destruction. My soul shall be joyful in the LORD. It shall rejoice in his salvation. All my bones shall say, “LORD, who is like you, who delivers the poor from him who is too strong for him; yes, the poor and the needy from him who robs him?” Unrighteous witnesses rise up. They ask me about things that I don’t know about. They reward me evil for good, to the bereaving of my soul. But as for me, when they were sick, my clothing was sackcloth. I afflicted my soul with fasting. My prayer returned into my own bosom. I behaved myself as though it had been my friend or my brother. I bowed down mourning, as one who mourns his mother."

"Yes, he loved cursing, and it came to him. He didn’t delight in blessing, and it was far from him. He clothed himself also with cursing as with his garment. It came into his inward parts like water, like oil into his bones. Let it be to him as the clothing with which he covers himself, for the belt that is always around him. This is the reward of my adversaries from the LORD, of those who speak evil against my soul. But deal with me, GOD the Lord, for your name’s sake, because your loving kindness is good, deliver me; for I am poor and needy. My heart is wounded within me. I fade away like an evening shadow. I am shaken off like a locust. My knees are weak through fasting. My body is thin and lacks fat. I have also become a reproach to them. When they see me, they shake their head. Help me, LORD, my God. Save me according to your loving kindness; that they may know that this is your hand; that you, LORD, have done it. They may curse, but you bless. When they arise, they will be shamed, but your servant shall rejoice. Let my adversaries be clothed with dishonor. Let them cover themselves with their own shame as with a robe. I will give great thanks to the LORD with my mouth. Yes, I will praise him among the multitude. For he will stand at the right hand of the needy, to save him from those who judge his soul."