प्रणवो ह्यपरं ब्रह्म प्रणवश्च परः स्मृतः ।अपूर्वोऽनन्तरो बाह्यो न परः प्रणवोऽव्ययः ॥
In plain words
Om is the lower Brahman, and Om — so tradition holds — is the higher as well. Nothing comes before it, nothing lies inside it, nothing stands outside it, nothing is beyond it. Om does not wear away.
Close to the Sanskrit
Praṇava indeed is the lower Brahman; and Praṇava is declared to be the higher. Having nothing before it, nothing within it, nothing outside it, nothing beyond it — Praṇava is imperishable.