Agniveshyagrihyasutra 1.1.2.23

1.1.2.23

agreṇottaraṃ paridhisandhimaśmānaṃ nidhāya dakṣiṇena pādena kumāramāsthāpayati ātiṣṭhemamaśmānamaśmeva tvam̐ sthiro bhava \

Having placed a millstone in front of the northern junction of the enclosing sticks, he makes the boy step on it with his right foot, [saying]: "Step on this stone; be firm like a stone;