Shiva Purana
रुद्रजाप्यमकार्षं वै परमध्यानमास्थितः ॥ सरितश्चोत्तरे पुण्ये ह्येकचित्तः समाहितः ॥ ३॥
He chanted the mantra of Rudra and became absorbed in supreme meditation The river is concentrated in the holy north with one mind.
english translation
rudrajApyamakArSaM vai paramadhyAnamAsthitaH ॥ saritazcottare puNye hyekacittaH samAhitaH ॥ 3॥
hk transliteration by Sanscript