A pure devotee of Lord Kṛṣṇa doesn't have to perform any of the ritualistic functions enjoined in the Vedas; nor is he required to worship any demigods. Being a devotee of Lord Kṛṣṇa, one is understood to have performed all kinds of Vedic rituals and all kinds of worship to the demigods. One does not develop devotional service for Kṛṣṇa by performing the Vedic ritualistic ceremonies or worshiping the demigods, but it should be understood that one who is engaged fully in the service of the Lord has already fulfilled all Vedic injunctions.
In order to stop all such activities by His devotees, Kṛṣṇa wanted to firmly establish exclusive devotional service during His presence in Vṛndāvana. Because He is the omniscient Personality of Godhead, Kṛṣṇa knew that the cowherd men were preparing for the Indra sacrifice, but as a matter of etiquette He began to inquire with great honor and submission from elder personalities like Mahārāja Nanda.