Brihadaranyaka Upanishad 1.44

अथेत्यभ्यमन्थत् — स मुखाच्च योनेर्हस्ताभ्यां चाग्निमसृजत — तस्मादेतदुभयमलोमकमन्तरतः — अलोमका हि योनिरन्तरतः ॥

athety abhyamathat — sa mukhach cha yoner hastabhyam chagnim asrijata — tasmad etad ubhayam alomakam antaratah — alomaka hi yonir antaratah ||

Then he rubbed his hands. From his mouth as the fire-pit and from his hands he created fire. Therefore both mouth and hands are hairless inside, for the fire-pit is hairless inside.

तब उसने हाथों को मथा। मुख को अरणि और हाथों से अग्नि सृजित की। इसीलिए मुख और हाथ — दोनों भीतर से रोमरहित हैं; क्योंकि अरणि भीतर से रोमरहित होती है।