Śatapatha Brāhmaṇa ("of a hundred paths") 3.9.1.5

3.9.1.5

tasmai kamekādaśinyā yajeta | evaṃ haiva prajayā paśubhirāpyāyata upainam prajāḥ samāvartante tiṣṭhante 'sya prajāḥ śriye 'nnādyāya sa vasīyāneveṣṭvā bhavatyetasmai kamekādaśinyā yajate

And as to why it comes after that for Sarasvatî,--Sarasvatî is speech, and Soma is food: he who is incomplete by (having only) speech, now becomes indeed an eater of food.