"There are so many they have invented. Just like Hare Kṛṣṇa mantra is prescribed in the śāstras, and they have invented so many. Although there is the name of the Supreme Lord, still you have to follow the śāstra. If you say Rāma Rāma Rāma, RādheRādhe Rādhe, Kṛṣṇa, there are so many mentioned. That is also name, but you have to follow the śāstra. Śāstra says:
Hare Kṛṣṇa Hare Kṛṣṇa Kṛṣṇa Kṛṣṇa Hare Hare
Hare Rāma Hare Rāma Rāma Rāma Hare Hare
You have to take that. Not that you can say, nitāi-gaura rādhe-śyāma, hare kṛṣṇahare rāma, no. Why? Is there any in the śāstra? No, you have invented. What is the value of your invention? You are not perfect. But they like that "It is my guru, I have got some followers, I invent some type of chanting." This is nonsense. You must follow, mahājano yena gataḥ sa panthāḥ [Cc. Madhya 17.186]. You cannot invent. "
Śrīmad-Bhāgavatam 5.5.14—Vṛndāvana, November 2, 1976