Saturdays, or Sani kilamai, in the Tamil Month Puratasi is considered highly auspicious for propitiating and worshipping Lord Venkateswara, Lord Shani and Navagrahas. It is believed that Lord Balaji will help those devotees observing Purattasi worship and fasting overcome difficulties created by Sani Bhagvan.
It is believed that Lord Vishnu appeared as Lord Balaji on earth in Puratasi month and He also returned to Vaikunata in the month. There is also a popular belief that Shani Bhagavan loses his powers in Puratassi month and therefore cannot create any trouble.
Most devotees observe a partial fast on Puratasi Saturdays – only a single meal is eaten on the day.
Devotees also offer Ghee Lamp or Ellu Lamp to Lord Shani in the month.