Khandogya-Upanishad: Seventh Prapathaka, Twenty-First Khanda

1. “When one performs all sacred duties, then one attends really on a tutor. One who does not perform his duties, does not really attend on a tutor. Only he who performs his duties, attends on his tutor. This performance of duties, however, we must desire to understand.”

“Sir, I desire to understand it.”