Thiruvennainallur is closely related with the history of Saivite Acharya Sundarar.. The saint was in his wedding attire to marry the daughter of Sadangavi Sivachariya. Lord Shiva of the temple intervened in the guise of an old man and claimed Sundarar as his slave and produced documentary evidence signed by his father to substantiate his claim. Sundarar stoutly refuted the claim and called the Lord a lunatic. Unmindful of the retortation of Sundarar, the Lord dragged Sundarar to the Temple and simply disappeared. Realizing that the old man was none other than the Lord himself, Sundarar shed tears of apology. The Lord asked Sundarar to sing on him and suggested that he could use the word Pitha (lunatic) for a start which he used while refuting his claim. That was the first famous hym of Sundarar on Lord beginning with the line "Pitha Pirai Soodi" (Oh! Lunatic Lord wearing the moon) reverently chanted by the devotees. Then he proceeded to the Shiva shrines throughout Tamilnadu and sung his praise.
After entering the temple, on the right side north a mandap could be seen, where the Lord and Sundarar argued and the Panchayat took place. People carry the sand from the place and keep it for their worship. Also the sandals which the lord wore while coming to claim Sundarar is also still available in the temple.
Text source: www.dinamalar.com/koil_english/35_Sri Krupapureeswarar Temple %e2%80%93 Thiruvennainallur.asp