Aśauca-vidhi (Rules of Impurity) within Śrāddha-kalpa — Chapter on Testing/Selecting Brahmanas and Honoring the Atithi
सांगुष्ठेन तथा पाद्यं नासुरेभ्यो यथा भवेत् / एतान्येव च सर्वाणि दानानि च विशेषतः
sāṃguṣṭhena tathā pādyaṃ nāsurebhyo yathā bhavet / etānyeva ca sarvāṇi dānāni ca viśeṣataḥ
应以拇指相应之法奉献洗足水(pādya),使其不落于阿修罗;尤以此等,正是诸般布施(于施祖仪 śrāddha 中)之要。