Without being empowered by Krishna, nobody can preach the holy name of the Lord. Krishna bhakti vina nahe nama pracarana. So without getting the power of attorney… Just like even one is qualified lawyer, he must get the power of attorney from the client, then he can speak. That is the law. Similarly, without being endowed with the power of attorney from Krishna, it is not possible to preach.

From Srila Prabhupada’s lecture on CC Madhya 20.105, New York, 11 July 1976