Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 8 · Marriage
विवाहः
द्वितीये मध्यमं श्रेष्ठं तृतीये नवके नृभम् ।तिस्रः पूर्वोत्तरा धातृयाम्यमाहेशतारकाः ॥ ४९९ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 499.
In the second nine it is middling. It is best when the man's star falls in the third nine. The three Purva and Uttara stars, with Bharani, Rohini and Ardra, are one group.
Simple meaning: Middle if the man's star is in the second nine, best in the third. A star group is named.
इति मर्त्यगणे ज्ञेयः स्यादमर्त्यगणः परः ।
That was the human group. The god group is Shravana, Punarvasu, Hasta, Swati, Revati, Anuradha, Ashvini, Pushya and Mrigashira.
रक्षोगणः पितृत्वाष्ट्रद्विदैवाग्नींद्रतारकाः ।
The demon group is Magha, Chitra, Vishakha, Krittika, Jyeshtha, Dhanishtha, Shatabhisha, Mula and Ashlesha.
दंपत्योर्जन्मभे चैकगणे प्रीतिरनेकधा ।
Same group means much love. God and human is middling. A demon with another group may put life at risk.