Maha Vrat, an auspicious Tithi Vrat, is dedicated to Lord Shiva. According to Puranas and sacred scriptures, Maha Vrat was observed by many ancient Kings.
Maha Vrat Vidhi
In Magh Maas or Chaitra Maas, ‘cow made of jaggery’ is offered to a Brahmin. And on Shukla Tritiya in the same month, jaggery is eaten by the performer. Fasting is done on Shukla Ashtami or Shukla Chaturdashi whenever Shravana Nakshatra coincides.
Strict rules are followed on Kartik Amavasya or Kartik Purnima. Nakt Vrat is observed and Payasa made of Ghee, Chandan and sugarcane juice is consumed. On the following Pratipada, Upvaas is observed; bhojan and dakshina is offered to eight or sixteen Shaiva Brahmins. Shivling is worshipped and Shivaling Abhishek is done with Panchagavya, Ghee, Honey and hot water and Naivedya is offered. Guru and Gurupatni are offered alms like gold and new clothes.
Upvaas and Vishnu Poojan are the main rituals for Pournamasi Tithi.
Performing this Vrata for 16 years would fetch the Vrati the long healthy life, beauty and wealth. And observance of this vrata for one year would cleanse the vrati of all sins they committed and would attain Swarga Loka (Heaven). If anyone does it for 12 years, they would attain Vishnu Loka ultimately.
Maha Vrat is mentioned in the Matsya Purana, Kalika Purana, Linga Purana, Vishnudharmottara Purana and Mundakopanishad.