Agni Purana (Jyotisha Selections) · by Vyasa
Chapter 3 · Name Letters and Chakras
युद्धजयार्णवः (चक्राणि)
देवा अकारवर्गे तु दैत्याः कवर्गमाश्रिताः ।नागाश्चैव चवर्गाः(र्गे) स्युर्गन्धर्वाश्च टवर्गजाः ॥ १० ॥
In the full Agni Purana this is chapter 132, verse 10.
The gods are in the a-group. The Daityas are in the ka-group. The Nagas are in the cha-group. The Gandharvas come from the hard ta-group.
Simple meaning: Each group of letters belongs to a kind of being: gods, Daityas, Nagas and Gandharvas.
तवर्गे ऋषयः प्रोक्ताः पवर्गे राक्षसाः स्मृताः ।
The next letter groups belong to sages, demons, goblins and humans.
देवेभ्यो बलिनो दैत्या दैत्येभ्यः पन्नगास्तथा ।
Each kind of being in the list is stronger than the one before. The sages are above the Gandharvas.
ऋषिभ्यो राक्षसाः शूरा राक्षसेभ्यः पिशाचकाः ।
Each group is stronger than the one before. A strong one should avoid a weak one.