Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 9 · Vastu, Griha Pravesha
वास्तु गृहप्रवेशश्च
वस्त्वायामदलं नाभिस्तस्मादध्यंगुलत्रयम् ।कुक्षिस्तस्मिन्न्यसेच्छंकुं पुत्रपौत्रविवर्धनम् ॥ ५७२ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 572.
Half the length of the plot is the navel. Three finger-widths past that is the belly. Fix the peg there. It makes sons and grandsons grow.
Simple meaning: Fix the peg at the belly point of the plot. It makes sons and grandsons grow.
चतुर्विंशत्त्रयोविंशत्षोडशद्वादशांगुलैः ।
The measure is 24, 23, 16 or 12 finger-widths for the four classes. The peg is dressed with gold and cloth.
खदिरार्जुनशालोत्थं युगयंत्रं तरूद्भवम् ।
The peg is made of wood such as khadira, arjuna, shala or red sandalwood.
शंकुं त्रिधा विभज्याद्यं चतुरस्रं ततः परम् ।
Make the peg in three parts: four-sided, eight-sided and 14-sided. It must be smooth and flawless.