Shiva Purana
अनाहतमनुच्चार्य्यं शब्दब्रह्म शिवं परम् ॥ ध्यायन्ते देवि सततं सुधिया यत्नतः प्रिये ॥ ३८ ॥
The unaffected and unpronounceable Brahman of sound is the Supreme Lord Shiva. O dear one, meditate on them constantly with intelligence and diligence.
english translation
anAhatamanuccAryyaM zabdabrahma zivaM param ॥ dhyAyante devi satataM sudhiyA yatnataH priye ॥ 38 ॥
hk transliteration by Sanscript