Shatapatha Brahmana 7.5.1.22

7.5.1.22

so 'bravīt | ayaṃ vāva mā sarvasmātpāpmana udabhārṣīditi yadabravīdudabhārṣīnmeti tasmādupumbhara udumbharo ha vai tamudumbara ityācakṣate paro 'kṣam paro 'kṣakāmā hi devā uru me karaditi tasmādurukaramurukaraṃ ha vai tadulūkhalamityācakṣate paro 'kṣam paro 'kṣakāmā hi devāḥ saiṣā sarveṣām prāṇānāṃ yoniryadulūkhalaṃ śiro vai prāṇānāṃ yoniḥ

He said, 'Verily this one has lifted me from out of all evil;' and because he said he has lifted me out (udabhârshît),' hence (the name) 'udumbhara;'--'udumbhara' doubtless being what is mystically called Udumbara, for the gods love the mystic. 'Wide space (uru) shall it make (karat) for me!' he said, hence 'urukara;' 'urukara' doubtless being what is mystically called 'ulûkhala' (the mortar); for the gods love the mystic. Now that mortar is the birth-place of all breaths; and the birth-place of the breaths being the head-