What are the benefits of chanting the names of Lord Vishnu?
Here are some quotes from Bhagavatam.
SB 12.3.51: My dear King, although Kali-yuga is an ocean of faults, there is still one good quality about this age: Simply by chanting the names of Kṛṣṇa, one can become free from material bondage and be promoted to the transcendental kingdom.
SB 11.5.36: Those who are actually advanced in knowledge are able to appreciate the essential value of this Age of Kali. Such enlightened persons worship Kali-yuga because in this fallen age all perfection of life can easily be achieved by the performance of saṅkīrtana.
SB 11.5.37: Indeed, there is no higher possible gain for embodied souls forced to wander throughout the material world than the Supreme Lord’s saṅkīrtana movement, by which one can attain the supreme peace and free oneself from the cycle of repeated birth and death.
SB 2.1.11: O King, constant chanting of the holy name of the Lord after the ways of the great authorities is the doubtless and fearless way of success for all, including those who are free from all material desires, those who are desirous of all material enjoyment, and also those who are self-satisfied by dint of transcendental knowledge.
SB 8.23.16: There may be discrepancies in pronouncing the mantras and observing the regulative principles, and, moreover, there may be discrepancies in regard to time, place, person and paraphernalia. But when Your Lordship’s holy name is chanted, everything becomes faultless.
SB 1.1.14: Living beings who are entangled in the complicated meshes of birth and death can be freed immediately by even unconsciously chanting the holy name of Kṛṣṇa, which is feared by fear personified.
SB 12.12.47: If when falling, slipping, feeling pain or sneezing one involuntarily cries out in a loud voice, “Obeisances to Lord Hari!” one will be automatically freed from all his sinful reactions.
SB 12.3.44: Terrified, about to die, a man collapses on his bed. Although his voice is faltering and he is hardly conscious of what he is saying, if he utters the holy name of the Supreme Lord he can be freed from the reaction of his fruitive work and achieve the supreme destination. But still people in the Age of Kali will not worship the Supreme Lord.
SB 11.2.40: By chanting the holy name of the Supreme Lord, one comes to the stage of love of Godhead. Then the devotee is fixed in his vow as an eternal servant of the Lord, and he gradually becomes very much attached to a particular name and form of the Supreme Personality of Godhead. As his heart melts with ecstatic love, he laughs very loudly or cries or shouts. Sometimes he sings and dances like a madman, for he is indifferent to public opinion.
SB 12.13.23: I offer my respectful obeisances unto the Supreme Lord, Hari, the congregational chanting of whose holy names destroys all sinful reactions, and the offering of obeisances unto whom relieves all material suffering.
You can also refer this section of Bhagavatam, it has many such verses. SB 6.2: Ajāmila Delivered by the Viṣṇudūtas
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