Revatīnandana: "Verse 25: One who is beyond duality and doubt, whose mind is engaged within, who is always busy working for the welfare of all sentient beings, and who is free from all sins achieves liberation in the Supreme (BG 5.25)."
Prabhupāda: Now, these things are very important things, "whose mind is engaged within, who is always busy working for the welfare of all sentient beings." This chanting of Hare Kṛṣṇa, it is welfare work for all sentient being, even the worms, the microbes, the cockroaches. So many living entities are within this room. By hearing this vibration of Hare Kṛṣṇa mantra they will be getting also the result. That is described in Caitanya-caritāmṛta. When Lord Caitanya questioned Haridāsa Ṭhākura about the efficacy of chanting, how he described? You will find it in the Teachings of Lord Caitanya. It is a fact. If you are chanting within this room and if you find nobody is coming to participate in the kīrtana, don't be disappointed. There are many germs, worms, cockroaches, within this room—they are being benefited. They are being benefited. You cannot find any place without any living entities. You just find out one hole. You will see, hundreds of ants are coming out. So living entities are in the air, in the water, in the holes, everywhere. And this vibration... Everyone, every living, entity has got his ear. So this sound is so powerful because it is spiritual that it will act even on the ants and the trees and birds and the bees, what to speak of human being. It is so nice thing. So those who are chanting... "One who is always busy working."