Shatapatha Brahmana · Chapter 14.8.6

satyasya brahmaṇaḥ stutibrāhmaṇam
āpa evedamagra āsuḥ/ tā āpaḥ satyamasṛjanta satyaṃ brahma brahma prajāpatimprajāpatirdevān - १४.८.६.
te devāḥ satyamityupāsate/ tadetattryakṣaraṃ satyamiti sa ityekamakṣaraṃ tītyekamakṣaramamityekamakṣaraṃ prathamottame akṣare satyammadhyato'nṛtaṃ tadetadanṛtaṃ satyena parigṛhītaṃ satyabhūyameva bhavati naivaṃvidvāṃsamanṛtaṃ hinasti - १४.८.६.
tadyattatsatyam/ asau sa ādityo ya eṣa etasminmaṇḍale puruṣo yaścāyaṃ dakṣiṇe'kṣanpuruṣastāvetāvanyo'nyasminpratiṣṭhitau raśmibhirvā eṣo'sminpratiṣṭhitaḥ prāṇairayamamuṣminsa yadotkramiṣyanbhavati śuddhamevaitanmaṇḍalaṃ paśyati nainamete raśmayaḥ pratyāyanti - १४.८.६.
ya eṣa etasminmaṇḍale puruṣaḥ/ tasya bhūriti śira ekaṃ śira ekametadakṣarambhuva iti bāhū dvau bāhū dve ete akṣare svariti pratiṣṭhā dve pratiṣṭhe dve ete akṣare tasyopaniṣadahariti hanti pāpmānaṃ jahāti ca ya evaṃ veda - १४.८.६.
atha yo'yaṃ dakṣiṇe'kṣanpuruṣaḥ/ tasya bhūriti śira ekaṃ śira ekametadakṣarambhuva iti bāhū dvau bāhū dve ete akṣare svariti pratiṣṭhā dve pratiṣṭhe dve ete akṣare tasyopaniṣadahamiti hanti pāpmānaṃ jahāti ca ya evaṃ veda - १४.८.६.