Agni Purana (Jyotisha Selections) · by Vyasa
Chapter 3 · Name Letters and Chakras
युद्धजयार्णवः (चक्राणि)
सिद्धः साध्यः सुसिद्धश्च सर्वे ते फलदायकाः ।अरिर्मृत्युश्च द्वावेतौ वर्जयेत्सर्वकर्मसु ॥ ) ॥ ८ ॥
In the full Agni Purana this is chapter 132, verse 8.
Siddha, Sadhya and Susiddha all give results. Ari and Mrityu, these two, are to be avoided in all work.
Simple meaning: Siddha, Sadhya and Susiddha give results. Avoid Ari and Mrityu in all work.
अकारान्तं यथा प्रोक्तम इ उ ए विदुस्तथा ।
The rows of the other vowels work like the first. Next come the eight letter groups.
देवा अकारवर्गे तु दैत्याः कवर्गमाश्रिताः ।
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.