Hiranyakeshigrihyasutra 2.5.14.5

2.5.14.5

athānnasya juhoti \ iyameva sā yā prathamā vyauchat \ ekāṣṭakā tapasā tapyamānaā \ yā prathamā vyauchat \ iti \5\

Then he makes oblations of (other) food with (the verses), 'The one who shone forth as the first,' 'The Ekâshtakâ, devoting herself to austerities,' 'She who shone forth as the first' (Taitt. Samhitâ IV, 3, 11, I. 3. 5).