The Māheśvarī-Sūtrāṇi are fourteen sounds which contain all the letters of the Sanskrit alphabet.

Lord Shiva, when he performed the cosmic dance called Tandav Nritya for the sages, fourteen sounds (Maheshwari Sutras) were heard from his Damaru (musical instrument), which came to be known as the Śivasūtrajālam..

On hearing these sounds, sage Panini by the grace of Lord Maheshwara i.e. Shiva composed the work on Sanskrit grammar in a book called the Ashtadhyayi, which means eight chapters.

Maheshwari Sutras (Māheśvarī-Sūtrāṇi), also known as the Shiva Sutras are considered to be the foundation of Sanskrit. Sanskrit Varnamala has been created from the Maheshwari Sutras.

The above is derived from the following:

नृत्तावसाने नटराज-राजो ननादढक्काम् नवपञ्चवारम्।
उद्धर्त्तुकामो सनकादिसिद्धादिनेतद्विमर्शे शिवसूत्रजालम्॥

Nṛttāvasāne naṭarāja-rājo nanādaḍhakkām navapañcavāram।
Uddharttukāmo sanakādisiddhādinetadvimarśe śivasūtrajālam॥