Bṛhadāraṇyaka Upaniṣad ("Great Forest Teaching") 1.4.16

1.4.16

atho ayaṃ vā ātmā sarveṣāṃ bhūtānāṃ lokaḥ sa yajjuhoti yadyajate tena devānāṃ loko'tha yadanubrūte tena ṛṣīṇāmatha yatpitṛbhyo nipṛṇāti yatprajāmicchate tena pitṝṇāmatha yanmanuṣyānvāsayate yadebhyo'śanaṃ dadāti tena manuṣyāṇāmatha yatpaśubhyastṛṇodakaṃ vindati tena paśūnāṃ yadasya gṛheṣu śvāpadāvayām̐syā pipīlikābhya upajīvanti tena teṣāṃ loko yathā ha vai svāya lokāyāriṣṭimicchedevam̐ haivaṃvide sarvāṇi bhūtānyariṣṭimicchanti tadvā etadviditaṃ mīmām̐sitam

Now verily this Self (of the ignorant man) is the world of all creatures. In so far as man sacrifices and pours out libations, he is the world of the Devas; in so far as he repeats the hymns, &c., he is the world of the Rishis; in so far as he offers cakes to the Fathers and tries to obtain offspring, he is the world of the Fathers; in so far as he gives shelter and food to men, he is the world of men; in so far as he finds fodder and water for the animals, he is the world of the animals; in so far as quadrupeds, birds, and even ants live in his houses, he is their world. And as every one wishes his own world not to be injured, thus all beings wish that he who knows this should not be injured. Verily this is known and has been well reasoned.