Everyone should be engaged in preaching the cult of Kṛṣṇa consciousness. In other words, when disciples are grown up and are able to preach, the spiritual master should retire and sit down in a solitary place to write and execute nirjana-bhajana. This means sitting silently in a solitary place and executing devotional service. This nirjana-bhajana, which is the silent worship of the Supreme Lord, is not possible for a neophyte devotee. Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura never advised a neophyte devotee to go to a solitary place to engage in devotional service. Indeed, he has written a song in this connection:
duṣṭa mana! tumi kisera vaiṣṇava?
pratiṣṭhāra tare, nirjanera ghare,
tava hari-nāma kevala kaitava
"My dear mind, what kind of devotee are you? Simply for cheap adoration you sit in a solitary place and pretend to chant the Hare Kṛṣṇa mahā-mantra, but this is all cheating." Thus Bhaktisiddhānta Sarasvatī Ṭhākura advocated that every devotee, under the guidance of an expert spiritual master, preach the bhakti cult, Kṛṣṇa consciousness, all over the world. Only when one is mature can he sit in a solitary place and retire from preaching all over the world. Following this example, the devotees of the International Society for Krishna Consciousness now render service as preachers in various parts of the world. Now they can allow the spiritual master to retire from active preaching work. In the last stage of the spiritual master's life, the devotees of the spiritual master should take preaching activities into their own hands. In this way the spiritual master can sit down in a solitary place and render nirjana-bhajana.
(Srimad Bhagavatam----4:28:33----purport).

In this verse the words dayā jīveṣu, meaning "mercy to other living entities," indicate that a living entity must be merciful to other living entities if he wishes to make progress in self-realization. This means he must preach this knowledge after perfecting himself and understanding his own position as an eternal servant of Kṛṣṇa. Preaching this is showing real mercy to living entities. Other types of humanitarian work may be temporarily beneficial for the body, but because a living entity is spirit soul, ultimately one can show him real mercy only by revealing knowledge of his spiritual existence. As Caitanya Mahāprabhu says, jīvera 'svarūpa' haya-kṛṣṇera 'nitya-dāsa': (CC.2:20:108) "Every living entity is constitutionally a servant of Kṛṣṇa." One should know this fact perfectly and should preach it to the mass of people. If one realizes that he is an eternal servant of Kṛṣṇa but does not preach it, his realization is imperfect. Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura therefore sings, duṣṭa mana, tumi kisera vaiṣṇava? pratiṣṭhāra tare, nirjanera ghare, tava hari-nāma kevala kaitava: "My dear mind, what kind of Vaiṣṇava are you? Simply for false prestige and a material reputation you are chanting the Hare Kṛṣṇa mantra in a solitary place." In this way people who do not preach are criticized. There are many Vaiṣṇavas in Vṛndāvana who do not like preaching; they chiefly try to imitate Haridāsa Ṭhākura. The actual result of their so-called chanting in a secluded place, however, is that they sleep and think of women and money.
(Srimad Bhagavatam----4:29:1b----purport).

Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura explains in his Anubhāṣya, "A person who has attracted the attention of the spiritual master by his sincere service likes to dance and chant with similarly developed Kṛṣṇa conscious devotees. The spiritual master authorizes such a devotee to deliver fallen souls in all parts of the world. Those who are not advanced prefer to chant the Hare Kṛṣṇa mantra in a solitary place." Such activities constitute, in the language of Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura, a type of cheating process in the sense that they imitate the activities of exalted personalities like Haridāsa Ṭhākura. One should not attempt to imitate such exalted devotees. Rather, everyone should endeavor to preach the cult of Śrī Caitanya Mahāprabhu in all parts of the world and thus become successful in spiritual life. One who is not very expert in preaching may chant in a secluded place, avoiding bad association, but for one who is actually advanced, preaching and meeting people who are not engaged in devotional service are not disadvantages. A devotee gives the nondevotees his association but is not affected by their misbehavior. Thus by the activities of a pure devotee even those who are bereft of love of Godhead get a chance to become devotees of the Lord one day. In this connection Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura advises that one discuss the verse in Śrīmad-Bhāgavatam beginning naitat samācarej jātu manasāpi hy anīśvaraḥ (10.33.30), and the following verse in Bhakti-rasāmṛta-sindhu (1.2.255):
anāsaktasya viṣayān yathārham upayuñjataḥ
nirbandhaḥ kṛṣṇa-sambandhe yuktaṁ vairāgyam ucyate
One should not imitate the activities of great personalities. One should be detached from material enjoyment and should accept everything in connection with Kṛṣṇa's service.
(Sri Caitanya Caritamrta----1:7:92----purport).