Skandapurana 6.3.29.48

6.3.29.48

eṣā te kathitā tāta kāverī saritāṃ varā .
rudradehasamutpannā tena puṇyā saridvarā .. 29.48 ..

This has been told to you, dear one, the Kāverī, the best of rivers;
born from the body of Rudra, therefore she is the best, holy river.