The Supreme Personality of Godhead and His devotees who come to this world are executing a mission, and therefore sometimes they act in a way that is very difficult to understand. It is said, therefore, vaisnavera kriya-mudra vijneha na bujhaya: even if one is a very learned and intelligent scholar, he cannot understand the activities of a Vaisnava. A Vaisnava accepts anything favorable for executing his mission. But foolish persons, not knowing the purpose of such exalted Vaisnavas, indulge in criticizing them. That is forbidden. Since no one can understand what a Vaisnava does for the purpose of executing his mission, to criticize such a Vaisnava is the offense called sadhu-ninda.