Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 9 · Vastu, Griha Pravesha
वास्तु गृहप्रवेशश्च
शेषांशाः स्युश्च निर्माणे पुत्रपौत्रधनप्रदाः ।शिराः स्युर्वास्तुनो रेखा दिग्विदिग्मध्यसंभवाः ॥ ५५६ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 556.
The remaining parts, used for building, give sons, grandsons and wealth. The shiras (veins) of the plot are lines born from the directions, corners and middle.
Simple meaning: The other parts bring sons and wealth. The plot's veins are lines from directions and corners.
ब्रह्मभागाः पिशाचांशाः शिराणां यत्र संहतिः ।
The middle parts, the goblin parts and where the veins cross are the plot's weak spots.
मर्माणि संधयो नेष्टाः स्वस्थेऽप्येवं निवेशने ।
Avoid vital points and joints. Good months are Margashirsha, Phalguna, Vaishakha, Magha, Shravana and Kartika.
मासाः स्युर्गृहनिर्माणे पुत्रारोग्यधनप्रदाः ।
These months bring sons, health and wealth. Each letter group of the alphabet has its own direction.