Skandapurana 5.36.35

5.36.35

yaḥ staṃbhāya ripūṇāṃ vai prājāpatyaṃ ca vāruṇam ..
maṃtraṃ japeddvijaśreṣṭhāḥ samyakchraddhāparāyaṇaḥ ..
maṃtrasaṃstaṃbhitāstasya jāyaṃte sarvaśatravaḥ .. 35 ..

He who, devoted to right faith, O best of brahmins, recites the Prājāpatya and Vāruṇa mantras / for paralyzing his enemies / sees all his foes become paralyzed by the mantra. (35)