Skanda Purana 16.186.11

16.186.11

pāyasaṃ madhusaṃmiśraṃ bhakṣyabhojyaiḥ samanvitam ..
śeṣanāgaṃ samuddiśya vipraṃ yastatra bhojayet ..
koṭibhojyaṃ kṛtaṃ tena jāyate nātra saṃśayaḥ .. 11 ..

Whoever feeds a brahmin there with rice-pudding mixed with honey, / accompanied by various dishes and foodstuffs, dedicating it to Śeṣanāga, / has provided food for ten million [people]—there is no doubt about this.