The Mahesvara-sutrani, also known as the Siva-sutra-s, are fourteen verses that summarise the phonemes of Sanskrit language. It has been refered to in the Astadhyayi of Panini, and is generally regarded as the text responsible for Sanskrit syllables.
Within the tradition they are known as the Akṣarasamāmnāya, "recitation of phonemes," but they are popularly known as the Siva Sutras because they are said to have been revealed to Pāṇini by Lord Siva himself.
Legend has it that at the end of the great cosmic dance, Lord Siva was requested by the assembled siddha-s to reveal a divine language. In response the Lord of Dance, beat his hand drum fourteen times. The sounds that came out of this is considered the Mahesvara-sutrani.