Śatapatha Brāhmaṇa ("of a hundred paths") 2.4.2.6

2.4.2.6

naiva devā atikrāmanti | na pitaro na paśavo manuṣyā evaike 'tikrāmanti tasmādyo manuṣyāṇām medyatyaśubhe medyati vihūrcati hi na hyayanāya cana bhavatyanṛtaṃ hi kṛtvā medyati tasmādu sāyamprātarāśyeva syātsa yo haivaṃ vidvāntsāyamprātarāśī bhavati sarvaṃ haivāyureti yadu ha kiṃ ca vācā vyāharati tadu haiva bhavatyetaddhi devasatyaṃ gopāyati taddhaitattejo nāma brāhmaṇaṃ ya etasya vrataṃ śaknoti caritum

Neither the gods, nor the fathers, nor beasts transgress (this ordinance); some of the men alone transgress it. Hence whatever man grows fat; he grows fat in unrighteousness, since he totters and is unable to walk because of his having grown fat by doing wrong. One should therefore eat only in the evening and morning; and whosoever, knowing this, eats only in the evening and morning, reaches the full measure of life; and whatever he speaks, that is (true); because he observes that divine truth. For, verily, that is Brâhmanic lustre (tegas), when one knows to keep His (Pragâpati's) law.