My dear King, wherever people in any position perform their occupational duties of devotional service by chanting and hearing [śravaṇaṁ kīrtanaṁ viṣṇoḥ], there cannot be any danger from bad elements. Therefore there was no need for anxiety about Gokula while the Supreme Personality of Godhead was personally present.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
न यत्र श्रवणादीनि रक्षोघ्नानि स्वकर्मसु । कुर्वन्ति सात्वतां भर्तुर्यातुधान्यश्च तत्र हि
na yatra śravaṇādīni rakṣoghnāni svakarmasu | kurvanti sātvatāṃ bharturyātudhānyaśca tatra hi
SB 10.6.3