“If you become disobedient to God, then prakṛti or nature will give you trouble in so many ways. And as soon as you become submissive, surrender to Kṛṣṇa, the Supreme Personality of Godhead, there will be no more natural disturbances. I have heard in 1900, 1898—I was born in 1896—so I have heard, I have seen also, I remember, in Calcutta there was a very virulent type of plague epidemic in 1898. So Calcutta became devastated. All people practically left Calcutta. Daily hundreds and hundreds of people were dying. I was one year old or one and a half year old. I have seen what was happening, but there was plague epidemic. That I did not know. I, later on, I heard from my parents. So one bābājī, he organized saṅkīrtana, Hare Kṛṣṇa saṅkīrtana. When there was no other way, so he organized saṅkīrtana all over Calcutta. And in the, in saṅkīrtana, all people, Hindu, Muslim, Christian, Parsi, everyone joined. And they were coming, they were going road to road, street to street, entering in every house. So that Mahatma Gandhi Road, 151, you have seen. The saṅkīrtana party we received very nicely. There was light, and I was very small, I was also dancing, I can remember. Just like our small children sometimes dances. I remember. I could see only up to the knees of the persons who were joined. So the plague subsided. This is a fact. Everyone who knows history of Calcutta, the plague was subsided by saṅkīrtana movement.
Of course, we do not recommend that saṅkīrtana should be used for some material purpose, that is nāma-aparādha, nāma-aparādha. Shama sa bhakti kriya (?) pramāṇa. Saṅkīrtana, you can utilize saṅkīrtana for some material purpose, but that is not allowed.”

Srila Prabhupada’s lecture on Śrīmad-Bhāgavatam 1.10.5
Māyāpura, June 20, 1973