Shatapatha Brahmana 10.3.5.11

10.3.5.11

tadetadbrahmāpūrvamaparavat sa yo haitadevam brahmāpūrvamaparavadveda na hāsmātkaścana śreyāntmamāneṣu bhavati śreyāṃsaḥ śreyāṃso haivāsmādaparapuruṣā jāyante tasmādyo'smājjyāyāntsyāddiśo'smātpūrvā ityupāsīta tatho hainaṃ na hinasti

This Brahman has nothing before it and nothing after it; and whosoever thus knows this Brahman to have nothing before it and nothing after it, than he there is no one higher among his equals in station; and ever higher will be the descendants that spring from him. Wherefore, if any one would be greater than he, let him reverentially approach the regions in front (to the eastward) of that one in this way, and he will do him no injury.