There are many stories related to Monday (Somavara) fast. The first story says once upon a time there was a poor Brahmin who has nothing to sustain his family. Being requested by his wife the Brahman decided to go out for earning and arranging some food for his family. He left home with a brass pot and string. The Brahman took shelter under a Peepal tree beside the road and meditated there for twelve years. The passers by offered him food. His prayers and Monday fast pleased Lord Shiva. He disguised himself as a mendicant and appeared with a Dandi (stick) in his hand. Lord Shiva blessed the Brahmin and asked him to wish some boon and Brahman asked for wealth for his family. The Dandi Swami said that worldly possessions are temporary but if he learn one Mantra he could acquire whatever he wants. The Mantra was, Tuesday, Wednesday, Thursday, Friday, Saturday and Sunday all are related to one or other deity. Lord Shiva is the deity of Monday. Whosoever knows this secret gets nine treasures of Kubera, the Lord of Wealth as also all the Riddhis and Siddhis i.e. prosperity, wealth etc.
Having got the Mantra the poor Brahman was very happy and went to his sister's house nearby. He asked his sisters to clean the house, put on new clothes and invite her neighbors. The Brahman then told her the Mantra. To the surprise of all who have gathered in that house, it was filled with variety of household articles and wealth. It was pleasant surprise for the Brahman also as he tested the Mantra for the first time. But he refused food at his sister's house, as he was elder. On way back home he met his Baniya friend. There he tested the power of the Mantra once again. When the Brahman finally returned to his village, his wife was not very happy to see her returning empty-handed. The Brahman told her about the Mantra given by Dandi Swami and by the grace of Lord Shiva their house was also filled with immense wealth. Brahman's wife was surprised to see such a wealth and asked Brahman what they will do with such a huge wealth. The Brahman replied that the wealth should be spent for the good of others. They dug wells along the road for the pedestrians to quench their thirst and arranged the marriages of the poor girls.
The second story is also connected to Monday (Somavara) fast. Those who observe Monday fast listen to this story in the afternoon after offering prayers to Lord Shiva. There was a wealthy merchant in the city, who in spite of having all the wealth, remained sad, as he had no son. The merchant started worshipping Lord Shiva and Parvati and fasting on Mondays. Goddess Parvati was very pleased by his devotion and persuaded Lord Shiva to grant his prayer. Shiva gave him the boon of a son but said that the son would be only alive for twelve years only. Fortunately the merchant could hear their conversation.
As time passed on merchant's wife gave birth to a beautiful son. They celebrated the birth of their son with a great pomp and distributed money, food and clothes among the poor. All prayed for the newborn baby's happy and long life. But the merchant was still sad, as he only knew the truth of what going to happen after twelve years and Yama, the death-god spares nobody. The merchant again started observing the Monday (Somavara) fast with great devotion and zest.
At the age of eleven the merchant's son looked quite smart and mature. All relatives including merchant's wife wanted that he should be married with a beautiful girl. But the merchant sent him to Kashi with his maternal uncle to earn spiritual knowledge. They arranged devotional gathering on the way to Kashi at every halt and distributed alms among the beggars, also arranged best foods for the Brahamans and made enough offerings to them.
One day they reached in the capital of the king. The king's daughter was getting married. The bridegroom party also arrived there but they were extremely embarrassed as the groom was one-eyed. The groom's father was a rich man. He sends his men in search of a beautiful boy and got the merchant's son. He offered him huge money to replace the groom for the few hours during the marriage took place. The merchant's son married the princess in front of the holy fire and wrote the true story in her scarf. The bride noticed it later and refused to go with the marriage party. So the marriage party went without the newly married princess.
After the marriage they went to Kashi. The maternal uncle arranged for the boy's spiritual studies and also arranged devotional gathering and gave donations everyday for the well-being of the boy.
At the last day of his twelfth year, the merchant's son felt pain in the chest. His maternal uncle was performing the religious rites as per the routine. He found the boy death inside the room but kept silent until the religious routine was over. When everything was over he started crying. Many people gathered around him and shared his grief. Shiva and Parvati were also passing by that house. When Parvati heard this crying her motherly heart was full of pathos and she begged to Lord Shiva for the life of that dead boy. Shiva sprinkled Ganga water on his body and the got up as if he was in a deep sleep.
The spiritual education of the merchant's son was over. They started return journey. When they came to the city where the boy was married the king recognized him. He took the boy to his palace and the boy left along with his beautiful wife and a lot of dowry.
The boy reached his own city along with the bride. His parents were sitting on the rooftop of the house. They decided if their sin did not come back they would commit suicide by jumping down from the roof. The merchant's son went up to the roof and touched his parents' feet. All of them were very happy.
The third story is related to breaking Monday fast. It is said that strong belief in Lord Shiva brings prosperity and non-believers get sufferings. If the husband and wife have the same belief they lead a happy life. Even repentance at some stage is good.
Once Lord Shiva visited the famous city of Amaravati. Parvati also accompanied him. The divine couple stayed in a beautiful temple, where they were playing chess. Parvati asked the priest of the temple who will win. The priest was not much serious. He replied that Lord will win. But eventually Parvati won the game. She then cursed the priest that he would turn into a leper. The priest had loathful leprosy and spent a miserable life. After some time few fairies descended on earth and pitied the fate of the priest. The priest told them the whole story and advised him to observe Monday fasts for sixteen weeks unintereptedly. On the seventeenth week he must prepare some holy food by mixing flour with ghee and gur(molasses) and distribute the Prasad among the members of the family and take someby himself. The Brahaman follwed the instructions and was free from leprosy. Parvati and shiva came to that temple again. When they saw the Brahaman leading a normal life they were eager to know the reason. After the Brahaman explained everything Parvati was very delighted and enthusiastic. She started observing the Vrata for sixteen weeks. From Parvati, her son Katikeya came to know about Monday fasting and he kept the same, which helped him to be reunited with a Brahaman friend, who went to foreign land for a long time and returned hale and hearty. This Brahaman wanted to have a good wife and started observing Monday fast after knowing the modalities from Kartikeya. On seventeenth Monday he went to city. There the show of King's daughter marriage was going on, which he joined. The beautifully decorated elephant of the king incidentally garlanded him and he was married to the princess. On the honeymoon night, the princess wanted to know from her husband how it was possible. The Barhaman explained the glory of the Monday fast and bride too decided to observe it for the sixteen consecutive Mondays and got a beautiful son. As the son grew up he came to about the mystery of his birth from his mother and he also resolved to observe the fast to gain a kingdom for his parents. Incidentally a king's messenger from the neighbouring kingdom came in search of the bridegroom for the princes and offered this boy to marry her. The boy agreed and was married to the princess. After the death of the former king he became the king of the entire kingdom.
The new- king continued his fasts for the next sixteen Mondays. On the seventeenth Monday he arranged a large prayer party at the temple. The king requested his queen to accompany him in breaking fast after taking the Prasad from the priest. The queen denied and the king had to go alone. He heard an oracle who echoed with the instruction to turn out the queen from the palace or otherwise there would be severe destruction.
The king returned to the palace and called in a conference with his ministers and told about the oracle. The ministers agreed with him heavy heartedly and the queen was ultimately turned out.
The queen left the palace bare footed with worn out clothes. She faced many calamities of her destiny. First she tried to help an old woman who was carrying spindles over her head. But as soon as the queen took the spindles, a strong wind blew them. The old lady asked her to go away. The queen then went into an oilman's house. But as soon as she stepped in, the oil pots cracked and oil began to flow in the ground. The oilman immediately turned her out. She went to river to quench her thirst but the water dried up as soon as she touched the water. The queen then went into a deep jungle and saw a tank of water. As she went down to drink the water, the crystal clear water turned muddy. She cursed her fate and drank a few drops of that muddy water. As she was tired and wanted to take rest under a shady tree, all the leaves of the tree fall off and the tree became leafless. The cowherd boys saw the whole incident and narrated it to a priest in the nearby temple. The priest called for the woman and was surprised to see her royal features. He provided shelter to her but soon he was also fed up as whatever the woman touched be it milk, food or water became impure. The priest asked the woman the reason behind this and the woman narrated how it happened after she has rejected to attend Monday fast prayer. The priest understood that it was due to Shiva's curse and advised her to observe the Monday fasting for the sixteen Mondays. The queen realized her mistakes and started keeping fasts on Mondays. On the seventeenth Monday the king thought about the condition of the queen and send his courtiers to search for them. When the courtiers reached the temple where the queen was residing, the priest denied to hand over the queen. He asked the king to come to take his queen with him. The king came to the temple and admitted that he expelled his queen to avoid Shiva's rage. The royal couple then returned to the palace and the queen got the royal welcome. Food and money was distributed among the poor. The king and queen started observing Monday fasting regularly and lived a long happy life. After their death they found the abode of Lord Shiva.
It is told that those who observe fasting for sixteen Mondays, observe worldly pleasures as well as get destiny to the abode of Lord Shiva, Shivapuri after the death.