Śatapatha Brāhmaṇa ("of a hundred paths") 13.4.2.12

13.4.2.12

atha tṛtīyāṃ nirvapati savitre satyaprasavāya dvādaśakapālam puroḍāśameṣa ha vai satyaḥ prasavo yaḥ savituḥ satyena me prasavenemaṃ yajñam prasuvāditi

He then prepares a third (offering)--a cake on twelve potsherds to Savitri Satyaprasava ('of true impulse'); for that, indeed, is the true impulse which is Savitri's: 'May he impel with true impulse this my sacrifice!' so he thinks.