Purattasi is a holy month in the Tamil calendar in the same way Shravan month is holy for north Indians. The month of Shravan is dedicated to the worship of Lord Shiva among north Indians while the Tamil month of Purattasi is dedicated to the worship of Lord Vishnu, also called Perumal or Maayon in south India. This month is observed from mid-September to mid-October. During Purattasi, most Tamil Hindus observe fast on all the 5 Saturdays that fall in this month.
People are supposed to avoid non-vegetarian food in Purattasi. Some devotees observe a partial fast for the entire month and others may choose to observe a total fast on all the 5 Saturdays. They also avoid smoking and drinking. The practice is called Purattasi Vratham. In the scientific sense, it’s actually good to avoid non-vegetarian food in this month as people are prone to getting diseases due to climate changes and it’s also a fact that diseases can easily spread through animals. The monsoons will be very active during this season, and this may cause water-borne diseases like cholera, hepatitis, and gastritis.
To Hindus generally, Saturdays are quite important as the day is dedicated to worshipping Lord Vishnu. Purattasi Viratham or Purattasi Sani is very holy and special for Vishnu. On Purattasi Saturdays, many kinds of dishes are prepared. Devotees make Mavilakku, which is a lamp made using rice flour, ghee, and jaggery. The belief is that Lord Balaji (Vishnu) smiles on the devotees through the light from the lamp. Fasting purifies the mind and body and helps us to attain the abode of the Lord. Devotees also chant hymns dedicated to Lord Vishnu on these days.
It is believed that Vishnu descended on the hills of Tirupati in the month of Purattasi. At Tirupati, the annual Brahmotsavam is conducted during this month as also the festival of Ayudha Pooja (Dussehra). Tamilians who observe this fast visit Tirupati in this month. The Nava Tirupati will be present along the banks of the holy Thamirabharani river and the 108 Divya Desams. According to one belief, those who observe this Vratham for 108 Saturdays in their lifetime will attain Vaikunta or Vishnu’s abode.