The Lord never deviates from His word of honor. When He gives assurance for protection, the promise is executed in all circumstances. It is the duty of the pure devotee to be fixed in the discharge of the duty entrusted to him by the Lord or the Lord's bona fide representative, the spiritual master. The rest is carried on by the Lord without a break.
(Srimad Bhagavatam--------1:16:26-30-------purport).

In the impure state of a living being, the various senses are fully engaged in mundane affairs. If the ear is not engaged in the service of the Lord by hearing about Him from Bhagavad-gītā or Śrīmad-Bhāgavatam, certainly the holes of the ear will be filled with some rubbish. Therefore the messages of Bhagavad-gītā and Śrīmad-Bhāgavatam should be preached all over the world very loudly. That is the duty of a pure devotee who has actually heard about them from the perfect sources. Many want to speak something to others, but because they are not trained to speak on the subject matter of Vedic wisdom they are all speaking nonsense, and people are receiving them with no sense.
(Srimad Bhagavatam--------2:20:30-------purport).

Thus the spiritual master is not different from the Supersoul sitting within the heart. An uncontaminated soul or living entity can get a chance to meet the Paramātmā face to face. Just as one gets a chance to consult with the Paramātmā within his heart, one also gets a chance to see Him actually situated before him. Then one can take instructions from the Supersoul directly. This is the duty of the pure devotee: to see the bona fide spiritual master and consult with the Supersoul within the heart.
(Srimad Bhagavatam--------4:28:52-------purport).

This is the mentality of one who is becoming a pure devotee. When one is elevated to the platform of devotional service by the grace of the Lord and the spiritual master, one first regrets his past sinful activities. This helps one advance in spiritual life. The Viṣṇudūtas had given Ajāmila the chance to become a pure devotee, and the duty of a pure devotee is to regret his past sinful activities in illicit sex, intoxication, meat-eating and gambling. Not only should one give up his past bad habits, but he must always regret his past sinful acts. This is the standard of pure devotion.
(Srimad Bhagavatam--------6:2:27-------purport).