Bhagavad Gita · 15.16

द्वाविमौ पुरुषौ लोके क्षरश्चाक्षर एव च।क्षरः सर्वाणि भूतानि कूटस्थोऽक्षर उच्यते॥

dvāv imau puruṣhau loke kṣharaśh chākṣhara eva cha kṣharaḥ sarvāṇi bhūtāni kūṭa-stho 'kṣhara uchyate

There are two types of beings in this world — the perishable and the imperishable. All living beings are perishable, but the unchanging soul is called imperishable.

— Bhagavad Gita 15.16

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)