Shiva Purana
सर्वार्थसाधकं तस्मादेकं ब्रह्मैतदक्षरम् ॥ तेनोमिति जगत्कृस्नं कुरुते प्रथमं शिवः॥ ६॥
It is the imperishable Brahman, the means of attaining all objects. Śiva creates universe at the outset saying “Om”.
english translation
sarvArthasAdhakaM tasmAdekaM brahmaitadakSaram ॥ tenomiti jagatkRsnaM kurute prathamaM zivaH॥ 6॥
hk transliteration by Sanscript