Famous expression from the Mahopanishad (VI.72).

This expresses sarvātmā bhāva. Seeing everything as oneself, knowing that the self permeates everything. Since they are all the same, we can see all people as one family. This expresses self-evident non-dual love/devotion (parabhakti).

Even at the level of relative empirical reality (vyāvahārika satya) we can speak of one household, one economy, one ecology, one entropy, one universe in which everything interacts and is interdependent.