Hiranyakeshigrihyasutra 2.4.12.1

2.4.12.1

bhuñjānānsamīkṣate \ brahmaṇi ma ātmāmṛtatvāya \ iti \1\

While they are eating, he looks at them with (the words), 'My soul (âtman) dwells in the Brahman that it may be immortal.'
When they have eaten (and go away), he goes after them and asks for their permission to take the remains of their meal (for the rites which he is going to perform). Then he takes a water-pot and a handful of Darbha grass, goes forth to a place that lies in a south-easterly intermediate direction, spreads the Darbha grass out with its points towards the south, and pours out on that (grass) with downward-turned hands, ending in the south, three handfuls of water, with (the formulas), 'May the fathers, the friends of Soma, wipe themselves! May the grandfathers... the great-grandfathers, the friends of Soma, wipe themselves!' or, 'N.N.! Wash thyself! N.N.! Wash thyself!'