Bhagavad Gita · Chapter 2: The Path of Understanding
Bhagavad Gita 2.30
देही नित्यमवध्योऽयं देहे सर्वस्य भारत ।
तस्मात्सर्वाणि भूतानि न त्वं शोचितुमर्हसि ॥
dehī nityamavadhyo'yaṃ dehe sarvasya bhārata | tasmātsarvāṇi bhūtāni na tvaṃ śocitumarhasi ||
The embodied self in everyone's body can never be killed, Arjuna. Therefore you should not grieve for any being.
Modern context
Krishna sums up the teaching on the self in one line: the one who dwells in every body cannot be killed. Notice the words 'of everyone' and 'all beings'. The same dignity is present in each person without exception, friend or opponent. That is the firmest basis there is for respecting others.