“Om Namo Narayanaya” is the main mantra of Sri Vaishnavism. This once secret mantra was originally made available to the world through the grace of Ramanuja Acharya. Guru Periya Nambi asked Srimad Ramanuja to go to Thirukoshtiyur Nambi to learn from him the secret to attain Moksha. Ramanuja went to Thirukoshtiyur Nambi’s house and prostrated before him and put up his request to him. Thirukoshtiyur Nambi looked at him and said, “I do not think you are eligible to know about it, as of now. You go and come back again after some time.” Ramanuja returned to Srirangam with much disappointment and made eighteen trips to Thirukoshtiyur by walk and each time he was sent back.
Looking at Ramanuja’s persistence one day Thirukoshtiyur Nambi said, “I will now incite the Ashtakshara Maha Mantra which will free the person who recites it from cycle for birth and death but, you have to keep it a secret never reveal it to anyone. If you do so you will go to hell.” Ramanuja was incited with the mantra. Ramanuja’s face was radiant and he was very happy. Next morning instead of returning to Srirangam he went to Thirukoshtiyur temple. On the way he called out to the people and told them to come to the temple and he would gift them a valuable gem which would give them Eternal Bliss. Ramanuja climbed up the steps and reached the top of the temple Gopuram.
He told the people that he was going to tell them about a Mantra that would free them from the circle of samsara. He loudly chanted “Om Namo Narayanaya” and asked the people to repeat it. People were all enthralled and repeated it. Thirukoshtiyur Nambi came to know about it and he fumed with rage. He came to the temple and shouted, “By giving initiation to you I have committed a sin. You are a traitor you will go to hell.” Ramanuja replied politely, “Acharya! I know that I will go to hell for not abide your command. But if thousands of people would be benefited by chanting this mantra, I would not mind going to hell.” When Nambi heard this he hugged Ramanuja and appreciated his broadmindedness and blessed him. so thirukkotiyur nambi called him as emperumanar