Sometimes the spiritual master, after accepting a disciple, must take charge of that disciple’s past sinful activities and, being overloaded, must sometimes suffer–if not fully, then partially– for the sinful acts of the disciple. To counteract the sinful reactions he accepts from the disciple, he has to see a bad dream. Nonetheless, the spiritual master is so kind that in spite of having bad dreams due to the sinful disciple, he accepts this troublesome business for the deliverance of the victims of Kali-yuga. After initiation, therefore, a disciple should be extremely careful not to commit again any sinful act that might cause difficulties for himself and the spiritual master. Before the Deity, before the fire, before the spiritual master and before the Vaisnavas, the honest disciple promises to refrain from all sinful activity. Therefore he must not again commit sinful acts and thus create a troublesome situation. The poor spiritual master is kind and merciful enough to accept a disciple and partially suffer for that disciple’s sinful activities, but Krishna, being merciful to His servant, neutralizes the reactions of sinful deeds for the servant who engages in preaching His glories.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Eighth Canto, Chapter 4 – Text 15
A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Ninth Canto, Chapter 9 – Text 5