Srimad Bhagavatam Canto 07, Chapter 09, Text 46

SB 7.9.46

 vyakhya-raho-japa-samadhaya apavargyah
prayah param purusa te tv ajitendriyanam
 varta bhavanty uta na vatra tu dambhikanam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
O Supreme Personality of Godhead, there are ten prescribed methods on the path to liberation — to remain silent, not to speak to anyone, to observe vows, to amass all kinds of Vedic knowledge, to undergo austerities, to study the Vedas and other Vedic literatures, to execute the duties of varnasrama-dharma, to explain the sastras, to stay in a solitary place, to chant mantras silently, and to be absorbed in trance. These different methods for liberation are generally only a professional practice and means of livelihood for those who have not conquered their senses. Because such persons are falsely proud, these procedures may not be successful.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
As stated in Srimad-Bhagavatam (6.1.15):
kecit kevalaya bhaktya
agham dhunvanti kartsnyena
 niharam iva bhaskarah
“Only a rare person who has adopted complete, unalloyed devotional service to Krsna can uproot the weeds of sinful actions with no possibility that they will revive. He can do this simply by discharging devotional service, just as the sun can immediately dissipate fog by its rays.” The real purpose of human life is to attain liberation from material entanglement. Such liberation may be achieved by many methods (tapasa brahmacaryena samena ca damena ca), but all of them more or less depend on tapasya, austerity, which begins with celibacy. Sukadeva Gosvami says that those who are vasudeva-parayana, who have fully surrendered to the lotus feet of Lord Vasudeva, Krsna, automatically achieve the results of mauna (silence), vrata (vows) and other such methods simply by discharging devotional service. In other words, these methods are not so powerful. If one takes to devotional service, all of them are very easily performed.
Mauna, for example, does not mean that one should just stop speaking. The tongue is meant for speaking, although sometimes, to make a big show, a person remains silent. There are many who observe silence some day in a week. Vaisnavas, however, do not observe such silence. Silence means not speaking foolishly. Speakers at assemblies, conferences and meetings generally speak foolishly like toads. This is described by Srila Rupa Gosvami as vaco vegam. One who wants to say something can show himself to be a big orator, but rather than go on speaking nonsense, better to remain silent. This method of silence, therefore, is recommended for persons very attached to speaking nonsense. One who is not a devotee must speak nonsensically because he does not have the power to speak about the glories of Krsna. Thus whatever he says is influenced by the illusory energy and is compared to the croaking of a frog. One who speaks about the glories of the Lord, however, has no need to be silent. Caitanya Mahaprabhu recommends, kirtaniyah sada harih: one should go on chanting the glories of the Lord twenty-four hours a day. There is no question of becoming mauna, or silent.
The ten processes for liberation or improvement on the path of liberation are not meant for the devotees. Kevalaya bhaktya: if one simply engages in devotional service to the Lord, all ten methods of liberation are automatically observed. Prahlada Maharaja’s proposal is that such processes may be recommended for the ajitendriya, those who cannot conquer their senses. Devotees, however, have already conquered their senses. Sarvopadhi-vinirmuktam tat-paratvena nirmalam: a devotee is already freed from material contamination. Srila Bhaktisiddhanta Sarasvati Thakura therefore said:
dusta mana! tumi kisera vaisnava?
pratisthara tare, nirjanera ghare,
tava harinama kevala kaitava
There are many who like to chant the Hare Krsna mantra in a silent, solitary place, but if one is not interested in preaching, talking constantly to the nondevotees, the influence of the modes of nature is very difficult to surpass. Therefore unless one is extremely advanced in Krsna consciousness, one should not imitate Haridasa Thakura, who had no other business than chanting the holy name always, twenty-four hours a day. Prahlada Maharaja does not condemn such a process; he accepts it, but without active service to the Lord, simply by such methods one generally cannot attain liberation. One cannot attain liberation simply by false pride.
Srimad Bhagavatam Canto 07, Chapter 09, Text 45
Srimad Bhagavatam Canto 07, Chapter 09, Text 47