Agni Purana (Jyotisha Selections) · by Vyasa
Chapter 2 · War Astrology: Yogas, Nakshatras
युद्धजयार्णवः (योगाः नक्षत्राणि)
मूलदेवेच्छया जाता शक्तिः पञ्चदशाक्षरा ।चराचरं ततो जातं यामाराध्याखिलार्थवित् ॥ ३ ॥
In the full Agni Purana this is chapter 124, verse 3.
From the will of the first god came a power of fifteen syllables. From her the moving and unmoving world was born. By worshipping her, one knows all things.
Simple meaning: From the first god's will came a fifteen-syllable power, and from her the world. Worshipping her gives all knowledge.
मन्त्रपीठं प्रवक्ष्यामि पञ्चपन्त्रसमुद्भवम् ।
The seat of mantras comes from five mantras, which hold the life and death of all mantras.
ऋग्यजुःसामाथर्वाख्यवेदमन्त्राः क्रमेण ते ।
The five mantras match the four Vedas and Sadyojata and the others, with Brahma, Vishnu and Rudra.
ईशः सप्तशिखा देवाः शब्दाद्याः पञ्च च स्वराः ।
Ishana, the seven-flamed gods, the five sense qualities and the five vowels are named. The root is Brahma.