The legend of Karwa is well known. According to the legend, a woman named Karwa was deeply devoted to her husband. One day while bathing, he was caught by a crocodile.
Karwa came running and bound the crocodile with a cotton yarn. She then went to Yama, the Lord of the death, and requested him to send the offending crocodile to hell. But, Yama refused to do so. Karwa threatened to curse him. Yama, afraid of being cursed by Pati-vrat (devoted) wife, readily accepted and sent the crocodile to Yamalok or hell, and blessed Karwa's husband with long life.
Karwa and her husband enjoyed many years of wedded bliss. The fact that Yama was afraid of being cursed by a devoted wife showed the power a good faithful woman!
Once upon a time, there was a queen by the name of Veeravati. She was the only sister of her seven loving brothers. On the occasion of the first Karwa Chauth after her marriage, she went to her parents' house. After sunrise, she observed a strict fast. However, the queen was too delicate and couldn't stand the rigors of fasting. The seven brothers, who loved her dearly, were very disturbed watching the distress of their sister and decided to end her fast by deceiving her. Then the brothers reflected a mirror through Pipal tree leaves. The sister, taken it as moon rise, broke the fast and took food. However, the moment the queen ate her dinner, she received the news that her husband, the king, was dead.
The queen rushed to her husband's palace and on the way, she met Lord Shiva and his consort, Goddess Parvati. Parvati told her that the king had died because the queen had broken her fast by watching a false moon. However, when the queen asked her for forgiveness, the goddess granted her the boon that the king would be revived but would be ill. She would have to undertake the Karva Chauth (Karwa Chauth) fast under strict rituals, and then only her husband would be completely revived to life.
When Veeravati reached the palace, she found the king lying unconscious with hundreds of needles inserted in his body. Each day, she managed to remove one needle from the king's body. Next year, on the day of Karva Chauth, only one needle remained embedded in the body of the unconscious King.
Veeravati, strictly followed all the rituals of Karva Chauth (Karwa Chauth), queen Veeravati regained the life of her husband. But on that day and when she went to the market to buy the Karwa for the puja, her maid removed the remaining needle from the king's body. The king regained consciousness, and mistook the maid for his queen. When Veeravati returned to the palace, she was made to serve as a maid.
However, Veeravati was true to her faith and religiously observed the ritual of Karva Chauth (Karwa Chauth). Once when the king was going to some other kingdom, he asked Veeravati (now maid) if she wanted anything. Veeravati asked for a pair of identical dolls. The king obliged and Veeravati singing a song "Roli ki Goli ho gayi... Goli ki Roli ho gayi" (the queen has turned into a maid and the maid has turned into a queen).
On being asked by the king as to why did she keep repeating that song, Veeravati narrated the entire story. The king repented and restored the queen to her royal status. It was only the queen's devotion and her faith that won her husband's affection and the blessings of Goddess Parvati.
The belief in this fast and its associated rituals goes back to the pre-Mahabharata times. As per Mahabharata, Arjun, a supreme warrior and one of the Pandavas, went to the Nilgiri Hills to offer his prayers and worship the gods. Draupadi, wife of the Pandavas, was accompanying him. The rest of the Pandavas faced many problems in Arjun's absence. On the way, Draupadi was struck with fear believing that she was alone in the forest with no one to protect her. Draupadi, out of desperation, remembered Lord Krishna (whom she treated as his brother) and she invoked him to appear before her and asked for help her out of this grave situation.
On listening to her fear and perplexity, Lord Krishna cited an example of Goddess Parvati. Parvati in a similar situation asked Lord Shiva's help. Lord Shiva explained to her that to ward off such apprehensions, a woman could observe a fast on Kartik Krishna Chaturthi as a remedy. Lord Krishna advised her to observe the fast of Karva Chauth (Karwa Chauth) fast and also assured her of the victory of the Pandavas. Draupadi followed the instructions and observed the fast with all its rituals. Consequently, the Pandavas were able to overcome their problems.
There is the story of the Satyavan and Savitri. When Lord Yama, came to procure Satyavan's soul, Savitri begged him to grant him life. When he refused, she stopped eating and drinking. Yamraj finally relented and asked Savitri that she could ask for any other boon except for the life of her husband. Savitri asked that she be blessed with children. Yama agreed. Being a Pati-Vrat wife, Savitri would never any other man, be the father of her children. Yama was left with no other choice but to restore Savitri's husband to life. Yama granted Savitri, her husband's life. To this day, Karva Chauth (Karwa Chauth) is celebrated with great faith and belief.