वेदादौ च प्रयोज्यं स्याद्वंदने संध्ययोरपि । नवकौटिजपाञ्जप्त्वा संशुद्धः पुरुषो भवेत् १८ ।
The Praṇava is to be used in the beginning of the Vyāhṛtis, mantras, in the beginning of the Vedas, and during the prayer at dawn and at dusk along with Bindu and Nāda. If the devotee repeats it nine crores of times he becomes pure.