A class on Srimad Bhagavatam 1.2.16 given by His Divine Grace A.C. Bhaktivedanta Swami Prabhupada on October 27, 1972 in Vrindavan, India.
A transcript of the class can be found here: https://goo.gl/SZDCkY.
Srimad Bhagavatam 1.2.16
śuśrūṣoḥ śraddadhānasya
vāsudeva-kathā-ruciḥ
syān mahat-sevayā viprāḥ
puṇya-tīrtha-niṣevaṇāt
O twice-born sages, by serving those devotees who are completely freed from all vice, great service is done. By such service, one gains affinity for hearing the messages of Vāsudeva.