'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.'

In plain words: A person truly follows a teacher only when they do their sacred duties. Without doing one's duties, a person does not truly follow the teacher. So we must learn about duty. Narada says he wants to learn it.