Shatapatha Brahmana 11.1.4.3

11.1.4.3

atha yatpūrvedyuḥ dugdhaṃ dadhi tadindrāya pradātre'tha tadānīṃdugdhe viṣṇave śipiviṣṭāyaitāṃstaṇḍulāñcūte caruṃ śrapayati caruru hyeva sa yatra kva ca taṇḍulānāvapanti

And the sour curds (from the milk) milked on the day before (he prepares) for Indra Pradâtri (the Bestower); and those (larger) rice-grains he cooks in boiled fresh milk as a pap for Vishnu Sipivishta (the Bald); for a pap it is whenever rice-grains are thrown (into milk or sour curds).