Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 9 · Vastu, Griha Pravesha
वास्तु गृहप्रवेशश्च
प्राकारांतः क्षितिं कुर्यादेकाशीतिपदं यथा ।मध्ये नवपदे ब्रह्मस्थानं तदतिनिंदितम् ॥ ५५४ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 554.
Inside the wall, divide the ground into eighty-one squares. The nine squares in the middle are Brahma's place. It is much condemned for building.
Simple meaning: Divide the ground into 81 squares. The middle nine are Brahma's place and are not for building.
द्वात्रिंशदंशाः प्राकारसमीयांशाः समंततः ।
There are 32 parts along the wall. Starting a house in the goblin part can bring sorrow and fear.
शेषांशाः स्युश्च निर्माणे पुत्रपौत्रधनप्रदाः ।
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.