Śatapatha Brāhmaṇa ("of a hundred paths") 5.3.5.3

5.3.5.3

agreṇa maitrāvaruṇasya dhiṣṇyam | śārdūlacarmopastṛṇāti somasya tviṣirasīti yatra vai soma indramatyapavata sa yattataḥ śārdūlaḥ samabhavattena somasya tviṣistasmādāha somasya tviṣirasīti taveva me tviṣirbhūyāditi śārdūlatviṣi mevāsminnetaddadhāti tasmādāha taveva me tviṣirbhūyāditi

He spreads a tiger-skin in front of the Maitrâvaruna's hearth, with (Vâg. S. X, 5), 'Thou art Soma's beauty.' For because when Soma flowed through Indra he (Indra) thereupon became a tiger, therefore he is Soma's beauty: this is why he says, 'Thou art Soma's splendour;'--'may my beauty become like unto thine!' He thus bestows the tiger's beauty on him: therefore he says, 'May my beauty become like unto thine!'