Wikipedia
Shabdamanidarpana , also spelled Śabdamaṇidarpaṇa, is a comprehensive and authoritative work on Kannada grammar written by Kesiraja in 1260 CE. This work, which literally means "Jewel-mirror of Grammar", remains to-date a comprehensive and authoritative work on Kannada grammar. The rules here are set forth in kanda metre and is followed by a prose commentary in vrutti (illustrative commentary by the author himself) and is considered a writing of high value. Though Kesiraja followed the model of Sanskrit grammar of the Katantra school and that of earlier writings on Kannada grammar, his work has an originality of its own.
Shabdamanidarpana is the earliest extant work of its kind, and narrates scientifically the principles of old Kannada language and is a work of unique significance.