The principle of matter [mahat-tattva] is the consciousness of the omnipresent Lord, as asserted by the experts, and Rudradeva is His ego. The horse, mule, camel and elephant are His nails, and wild animals and all quadrupeds are situated in the belt zone of the Lord.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
विज्ञानशक्तिं महिमामनन्ति सर्वात्मनोऽन्तःकरणं गिरित्रम् । अश्वाश्वतर्युष्ट्रगजा नखानि सर्वे मृगाः पशवः श्रोणिदेशे
vijñānaśaktiṃ mahimāmananti sarvātmano'ntaḥkaraṇaṃ giritram | aśvāśvataryuṣṭragajā nakhāni sarve mṛgāḥ paśavaḥ śroṇideśe
SB 2.1.35