Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 7 · Samskara Muhurtas
संस्कारमुहूर्ताः
तस्माद्गोमिथुनांशाश्च तुलाकन्यांशकाः शुभाः ।एवंविधे लग्नगते नवांशे व्रतमीरितम् ॥ ३७४ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 374.
So the Taurus navamsha (one-ninth part of a sign) is good. So are the Gemini, Libra and Virgo navamshas. When the lagna (rising sign) is in such a navamsha, the vrata (vow rite) is said to be good.
Simple meaning: Taurus, Gemini, Libra and Virgo navamshas are good for the thread ceremony.
त्रिषडायगतैः पापैः षडष्टांत्यविवर्जितैः ।
Bad planets in the 3rd, 6th or 11th. Good planets away from 6, 8, 12. Moon away from 6, 8, 12, 1.
स्वोच्चसंस्थोऽपि शीतांशुर्व्रतिनो यदि लग्नगः ।
Even an exalted Moon in the rising sign can make the boy poor and sickly.
स्फूर्जिते केंद्रगे भानौ व्रतिनां पितृनाशनम् ।
A fierce Sun in a corner house can harm the father. A fault-free rising sign is good.