King Prajapal asked Mahatapa about the reason why goddess Gauri- the epithet of power, had to take incaranation. Sage Mahatapa replied – “Goddess Gauri manifested from lord Narayan and was offered to Rudra as his consort by lord Brahma. Lord Brahma then instructed Brahma to begin creation but Rudra being free from all kinds of worldly attachment refused to oblige lord Brahma and engaged himself in austere penance. Goddess Gauri then merged her identity with Brahma, who later on created his seven ‘manas-putras’. In course of time, Gauri was born as the daughter of Daksha Prajapati and hence came to be known as ‘Dakshayani’.
Once Daksha Prajapati organised a grand yagya in which all the seven manasputras were assigned specific responsibilities. Meanwhile Rudra came out from his meditation and was extremely furious to see the earth occupied by countless creatures. He thought- ‘Brahma had requested me to create then who is responsible for all these creation? Who has dared to transgress my authority?’ As Rudra stood wondering, suddenly he heard the sound of the mantras being chanted at the yagya performed by Daksha. Now, Rudra’s fury crossed all limits resulting into the emergence of numerous spirits and ghosts from his ears. He then went to the oblation- site accompanied by the ghosts and started destroying it. Lord Vishnu tried to protest as a result of which a fierce battle was fought between both of them. It was only on lord Brahma’s intervention that both of them stopped fighting. Lord Brahma said- ‘From now onwards Rudra would become famous as ‘Har’ while Vishnu would be known as ‘Hari’. He then directed the deities to eulogize Rudra and give his due share of the yagya being performed by Daksha Prajapati.’
Rudra became pleased by deities’s eulogy and blessed them. This way Daksha Prajapati was able to accomplish his yagya with the blessings of Rudra. In course of time, Rudra married Gauri- the daughter of Daksha Prajapati. Once, Gauri went to her father’s place to attend a yagya ceremony against the wish of her husband. On seeing her, Daksha Prajapati started cursing Rudra. Gauri was so enraged by her father’s attitude that she gave up her life by jumping into the sacrificial fire meant for the yagya. Later on, she took rebirth as Parvati- the daughter of Himalaya. Parvati did an austere penance to get Shiva as her husband. Ultimately her desire was fulfilled and she became the consort of lord Shiva.
The tithi of tritiya is very deeply attached with the worship of goddess Parvati because all the important events of her life (birth, marriage, etc.) took place on this day. This is the reason why tritiya is attributed to the worship of goddess Parvati. A woman who observes a fast on this day enjoys a blissful married life. One important ritual related with the austerity of tritiya is avoiding the usage of salt on this day.