Keshava Aditya Temple, Varanasi

Once Lord Surya was travelling in the sky and from a distance he could see Adi Keshav (Lord Vishnu) worshipping a Shiv Ling. Being very curious, Lord Surya came down to the earth and after Adi Keshav finished the prayers, put forward a question to the latter.

Lord Surya asked when the entire world regards Lord Vishnu as Antaratma, the latter should be worshipped. Lord Surya was surprised why Lord Vishnu was worshipping Lord Shiva. To quell his anxiety, Lord Vishnu replied that in Kashi Kshetra Lord Shiva is the supreme Lord and he should be worshipped by every one.

Lord Vishnu extensively described the importance of Linga Pooja in Kashi inasmuch as a devotee who performs abhishek of a Shiv Ling and consumes the water as prasad, gets the punya of taking bath in all religious Teerths (Sacred Ponds). Lord Vishnu advised Lord Surya also to worship Lord Shiva in Ling form in Kashi.  (Kashi Khand, Chapter 51).

Lord Surya piously regarded Adi Keshav as his Guru for giving this sacred knowledge and Lord Surya came to be called as Keshava Aditya at that place.

According to Kashi Khand, a person who takes bath in Padodak Teerth (Koop) and worships Keshava Aditya gets rid of all sins.  Special importance is attached to Magh month (Jan 21-Feb 20) on any Saptami day (7^th day after Amavasya or Poornima) when it coincides with Sunday.  On such days, devotees are advised to take bath in Padodak Koop and worship Keshava Aditya.