Shiva Purana
वदेज्जयेत्त्रिधा मन्दमध्योच्छ्रायक्रमान्मुने॥ प्रणवम्पूर्व्वमुद्धत्य सृष्टिस्थितिलयक्रमात्॥ ६७॥
O sage, he shall recite the mantras in the low, medium and high tone beginning with the Praṇava in the order of creation, sustenance and dissolution.
english translation
vadejjayettridhA mandamadhyocchrAyakramAnmune॥ praNavampUrvvamuddhatya sRSTisthitilayakramAt॥ 67॥
hk transliteration by Sanscript