Todalatantra 3.8

3.8

śrīpārvatī uvāca
vada īśāna sarvajña sarvatattvavidāṃ vara
mantramārgeṇa deveśa kālikāyāḥ sudurlabham //

Pārvatī said: / Speak, O Īśāna, all-knowing one, best among knowers of all principles, / of the [practice] of Kālikā, exceedingly difficult to obtain, according to the path of mantras, O ruler of gods.