Manava Dharmashastra 3.179

3.179

nimantritena niyatātmanā bhavitavyamityasya vidherarthavādo'yam | yasmānnimantritān brāhmaṇān adṛśyena rūpeṇa pitara upatiṣṭhanti taccharīramanupraviśanti, yathā bhūtagrahāviṣṭam | vāyuvadanugacchanti | yathā vāyuḥ prāṇaḥ puruṣaṃ gacchantamalugacchati, na gacchantaṃ prāṇo jahāti, evaṃ pitaro vāyubhūtā bhavanti | tayā''sīnān brāhmaṇānupāsate | gacchatastvanugacchanti, upaviṣṭeṣūpaviśanti | nimantritā dvijā pitṛrūpāpannā bhavantītyarthaḥ | tasmānna svatantrairnimantritairbhavitavyam |

Medhātithi’s commentary (manubhāṣya):
The present verse supplies a recommendation in support of the injunction that the invited person should remain self-controlled.

Because ‘the Pitṛs,’—in their invisible forms —‘attend upon’—enter into the body of—‘the invited Brāhmaṇas;’ just in the same manner in which people are obsessed by evil spirits.

‘Like the wind they follow him;’—when a man moves along, the ‘wind’—in the form of his breath—follows him; and it does not leave him while he is moving; and the Pitṛs also are in the form of air.

‘So when they ’—the Brāhmaṇas—‘are seated,’ “they sit down;’ i.e., they move when the Brāhmaṇas move and sit down when they are seated. The meaning is that the invited Brāhmaṇas take the form of the Pitṛs; hence those invited shall not be unrestrained in their behaviour.—(189)