As per PADMA-PURANA: UTTARKHANDA: Chapter 232. The Raise of Goddess Laksmi:
Lord Shiva said:
He who, being restrained, would devoutly mutter the three names of Visnu, viz. Acyuta, Ananta, Govinda, beginning with Pranava (i.e. Om) and (also) ending with Om, has no fear of death, so also the great fear due to poison, disease and fire. The wise, restrained one, who would mutter the great hymn—the three names—does not have fear of Death; then from where else (can he have it)? Thus with (the muttering of) the three names I drank that poison.
The benefits of chanting the names of Lord Vishnu are mentioned in many other places, for example:
PADMA-PURANA: UTTARAKHANDA: Chapter 72. Merit of Reciting the Visnusahasranama
Mahabharata: Anusasana Parva: Section CXLIX (Vishnu Sahasranama)
PADMA-PURANA: BHUMIKHANDA: Chapter 87. A Hundred Names of Visnu or 'Vishnu Satanama'
PADMA-PURANA: UTTARAKHANDA: Chapter 71. Visnu's One Thousand Names or 'Vishnu Sahasranama'