Manava Dharmashastra 3.274

3.274

pitṛdveṣādapravartamānasya pravṛttyarthamidam | tristhānā vasvādyā devatāḥ pitaro'pi ya eva piṇḍabhājaḥ | ato devatātvenaite draṣṭavyāḥ | śrutireṣā śrūyate etadvede | ataḥ purātanī nityatvādvedasya |

Medhātithi’s commentary (manubhāṣya):
This verse is intended to prompt a man who, through ill-will towards his father, is disinclined to perform Śrāddhas.

The three grades of ancestors, to whom balls are offered, are the same as the Vasus and other gods; hence they should be looked upon as gods.

‘Such is the text’—this is found in the Veda; hence ‘ancient’—the Veda being eternal.—(284)