Shatapatha Brahmana 6.6.2.13

6.6.2.13

ghṛte nyuttā bhavati | agniryasyai yonerasṛjyata tasyai ghṛtamulbamāsīttasmāttatpratyuddīpyata ātmā hyasyaiṣa tasmāttasya na bhasma bhavatyātmaiva tadātmānamapyeti na vā ulbaṃ garbhaṃ hinastyahiṃsāyā ulbādvai jāyamāno jāyata ulbājjāyamāno jāyātā iti

It is soaked in ghee;--the inner membrane of the womb from which Agni was produced consisted of ghee: hence he now blazes up towards it, for it (the stick) is his self (body); and hence it (the krimuka) has no ashes: (Agni) himself now enters into his own self,--to avoid injury, for the inner membrane does not injure the embryo; and it is from the inner membrane that he who is born is born: 'When he (Agni) is born, may he be born from the inner membrane!' thus he thinks.