Chandogya Upanishad 7.13

'Memory surely is greater than Ākāśa. Therefore, even if many persons should assemble and if they should have no memory, they surely would not hear any sound, they would not think, they would not know. But surely, should they have memory, then they would hear, then they would think, then they would know. Through memory, indeed, one discerns one's sons, through memory one's cattle. Worship memory.

‘He who worships memory as Brahman becomes free to act as he wishes in the sphere within the reach of memory, he who worships memory as Brahman.’ ‘Revered sir, is there anything greater than memory?’ ‘Surely, there is something greater than memory.’ ‘Revered sir, communicate it to me.’