Aśauca-vidhi (Rules of Impurity) within Śrāddha-kalpa — Chapter on Testing/Selecting Brahmanas and Honoring the Atithi
वानप्रस्थाय कुर्वाणः पूजामात्रेण तुष्यते / गृहस्थं भोजयेद्यस्तु विश्वेदेवास्तु पूजिताः
vānaprasthāya kurvāṇaḥ pūjāmātreṇa tuṣyate / gṛhasthaṃ bhojayedyastu viśvedevāstu pūjitāḥ
A vānaprastha is satisfied by mere worship; but whoever feeds a householder thereby worships the Viśvedevas as well.