These are the necessary qualifications of a prospective candidate who can expect to be elevated to the position of a pure unadulterated devotee. Such a candidate must always seek the association of pure devotees. One should not be misled by a pseudodevotee. He himself must be plain and gentle to receive the instructions of such a pure devotee. A pure devotee is a completely surrendered soul unto the Personality of Godhead. He knows the Personality of Godhead as the supreme proprietor and all others as His servitors. And by the association of pure devotees only, one can get rid of all sins accumulated by mundane association. A neophyte devotee must faithfully serve the pure devotee, and he should be very much obedient and strictly follow the instructions. These are the signs of a devotee who is determined to achieve success even in the existing duration of life.
(Srimad Bhagavatam------1:5:29------purport).

Mahārāja Dhṛtarāṣṭra was tightly bound in a network of material affinities related to politics, economy and family attachment, and he did everything in his power to achieve so-called success in his planned projects, but he was frustrated from the beginning to the end so far as his material activities were concerned. And yet, despite his life of failure, he achieved the greatest of all success in self-realization by the forceful instructions of a pure devotee of the Lord, who is the typical emblem of a sādhu. The scriptures enjoin, therefore, that one should associate with sādhus only, rejecting all other kinds of association, and by doing so one will have ample opportunity to hear the sādhus, who can cut to pieces the bonds of illusory affection in the material world.
(Srimad Bhagavatam------1:13:29------purport).

The instructions of a pure devotee to his disciple are also very simple. No one feels any difficulty in following in the footsteps of a pure devotee of the Lord. Anyone who follows in the footsteps of recognized devotees, such as Lord Brahmā, Lord Śiva, the Kumāras, Manu, Kapila, King Prahlāda, King Janaka, Śukadeva Gosvāmī, Yamarāja and their followers in disciplic succession, very easily finds the door of liberation open.
(Krsna Book).

Therefore a devotee treats friends and enemies equally by trying to educate them both in Kṛṣṇa consciousness. Of course, atheistic men do not follow the instructions of pure devotees, but instead consider a devotee their enemy. A devotee, however, never creates a situation of friendship and enmity. Although Prahlāda Mahārāja was obliged to hear the instructions of Ṣaṇḍa and Amarka, he did not like the philosophy of friends and enemies, which forms the basis of politics. He was not interested in this philosophy.
(Srimad Bhagavatam------7:5:3------purport).