Śatapatha Brāhmaṇa ("of a hundred paths") 3.3.2.2

3.3.2.2

athāsyāṃ hiraṇyam badhnīte | dvayaṃ vā idaṃ na tṛtīyamasti satyaṃ caivānṛtaṃ ca satyamava devā anṛtam manuṣyā agniretasaṃ vai hiraṇyaṃ satyenāṃśūnupaspṛśāni satyena somam parāhaṇānīti tasmādvā asyāṃ hiraṇyam badhnīte

Thereupon he ties the piece of gold to this (finger). Now, twofold indeed is this (universe),--there is no third,--the truth and the untruth: the gods are the truth and men are the untruth. And gold having sprung from Agni's seed, he ties the gold to this (finger), in order that he may touch the twigs (of the Soma) with the truth, that he may handle the Soma by means of the truth.