Sri Sri Sankara along with his disciples once visited Sri Vishwanatha Temple at Kasi. After taking bath in Ganga he headed straight to the temple. At the temple in front of Lord Vishwanatha, Sri Sri Sankara began to seek pardon to the three sins he had committed. His disciples were surprised and wondered what those sins could be for which Acharya was doing Prayaschitta (Atonement).
One of the disciples out of curiosity to know about the three sins that Acharya had committed asked Sri Sri Sankara about it. Sri Sri Sankara explained, “Though I believe that Absolute is Sarvavyapta (Omnipresent) and had expressed so in many of my works, I have come all the way to Kasinagara to have His darshana, as if He was present only in Kasinagara. I have committed the sin of saying one thing and doing the other. This is my first sin.
Taittriya Upanishad says, “Yatho Vacho Nivartante Aprapya Manasa Sah.”(The words return and mind fails to comprehend Him). Though I knew that He is beyond the realm of thoughts and words, I have made an attempt of describing Him by words in “Sri Kasi Vishwanatha Ashtakam.” Again I have committed the sin of not practicing what I preached. This is my second sin.
Now the third sin, in my “Nirvana Shatakam” I had written clearly,
Na Punyam Na Papam Na Saukhyam Na Dukham
Na Mantro Na Teertham Na Veda Na Yajnaha
Aham Bhojanam Naiva Bhojyam Na Bhokta
Chidananda Rupah Shivoham Shivoham
I have neither higher nor lower merits. Nor pleasure or pain, I do not need sacred chants, nor I need to go on pilgrimages. I do not need scriptures, rituals, or sacrifices (yajnas). I am neither the enjoyed nor the enjoyer, nor enjoyment. I am the form of Consciousness-Bliss. I am auspicious, I am auspicious.
Yet, here I am standing in front of the Lord praying for the atonement of my sins. This is the third sin.
The profound insight in this episode in the life of Sri Sri Sankara’s reveals the importance of harmony in our thought, word, and deed. If one has the keenness to attain Absolute he has to maintain harmony in his thoughts as well as words and deeds. No matter how good our intentions are, the world looks for our presentation. But no mater how good our presentation is Absolute looks for our intentions. It is said, Manas Ekam vachas Ekam, karman Ekam Mahatmanam, Manas Anyatha vachas Anyatha, karman Anyatha Duratmanam. (Superior people are those who have perfect harmony in their thoughts, words and deeds, Inferior are those who lack harmony).
Source : https://www.speakingtree.in/blog/the-three-sins-of-sri-sri-sankara