Atma Shatakam or Nirvana Shatakam
When he was 8 years old Sri Adi Shankara (788 – 820 CE) was wandering through the forests searching for a Guru. He met Sri Govindapada, who asked him: “Who are you?”. In response, Sri Shankara, composed six verses in reply.
These verses are known as Atma Shatakam or Nirvana Shatakam. They clearly state who you are – Self-Knowledge. You exist, you know that you exist. That is self-knowledge. Just remain as that self-knowledge without following the thoughts that arise.
Here is a beautiful rendition of the Nirvana Shatakam