Srimad Bhagavatam Canto 10, Chapter 85, Text 12

SB 10.85.12

nasvaresv iha bhavesu
 tad asi tvam anasvaram
yatha dravya-vikaresu
 dravya-matram nirupitam
 
Translation: 
 
You are the one indestructible entity among all the destructible things of this world, like the underlying substance that is seen to remain unchanged while the things made from it undergo transformations.
Srimad Bhagavatam Canto 10, Chapter 85, Text 11
Srimad Bhagavatam Canto 10, Chapter 85, Text 13