The following lines are from the Mahabharata and are quoted portions from the text. Believers believe that regular chanting of the hymn can accrue benefits.
On avoiding evil, success in battles, and gaining affluence, pleasure, happiness and offspring:
vedantago brahmanasyat kshatriyo vijayeebhavet
vaishyo dhanasamrudhyasyat shudra sukhamavapniyat
Bhisma said, "Even thus have I recited to thee, without any exception, the thousand excellent names of the high-souled Kesava whose glory should always be sung. Anyone who hears the names every day or who recites them every day, never meets with any evil either here or hereafter. If a Brahmana does this he succeeds in mastering the Vedanta; if a Kshatriya does it, he is always successful in battles. A Vaisya, by doing it, becomes possessed of affluence, while a Sudra earns great happiness."
If one becomes desirous of earning the merit of righteousness, one succeeds in earning it (by hearing or reciting these names). If it is wealth that one desires, one succeeds in earning wealth (by acting in this way). So also the man who wishes for enjoyments of the senses succeeds in enjoying all kinds of pleasures, and the man desirous of offspring acquires offspring (by pursuing this course of conduct)."
On acquiring fame, prosperity, prowess, energy, strength, beauty, removing fear, avoiding calamity, and being cured of disease:
"That man who with devotion and perseverance and heart wholly turned towards him, recites these thousand names of Vasudeva every day, after having purified himself, succeeds in acquiring great fame, a position of eminence among his kinsmen, enduring prosperity, and lastly, that which is of the highest benefit to him (viz., emancipation Moksha itself). Such a man never meets with fear at any time, and acquires great prowess and energy. Disease never afflicts him; splendour of complexion, strength, beauty, and accomplishments become his. The sick become hale, the afflicted become freed from their afflictions; the frightened become freed from fear, and he that is plunged in calamity becomes freed from calamity."
The man who hymns the praises of that foremost of Beings by reciting His thousand names with devotion succeeds in quickly crossing all difficulties. That mortal who takes refuge in Vasudeva and who becomes devoted to Him, becomes freed of all sins and attains to eternal Brahman. They who are devoted to Vasudeva have never to encounter any evil. They become freed from the fear of birth, death, decrepitude, and disease."
On acquiring righteousness and intelligence, and avoiding the sins of evil:
"That man who with devotion and faith recites this hymn (consisting of the thousand names of Vasudeva) succeeds in acquiring felicity of soul, forgiveness of disposition, Prosperity, intelligence, memory, and fame. Neither wrath, nor jealousy, nor cupidity, nor evil understanding ever appears in those men of righteousness who are devoted to that foremost of beings. The firmament with the sun, moon and stars, the welkin, the points of the compass, the earth and the ocean, are all held and supported by the prowess of the high-souled Vasudeva. The whole mobile and immobile universe with the deities, Asuras, and Gandharvas, Yakshas, Uragas and Rakshasas, is under the sway of Krishna."
On the origins of the soul, the source of righteous behavior, and the basis of all knowledge and existence:
"The senses, mind, understanding, life, energy, strength and memory, it has been said, have Vasudeva for their soul. Indeed, this body that is called Kshetra, and the intelligent soul within, that is called the knower of Kshetra, also have Vasudeva for their soul. Conduct (consisting of practices) is said to be the foremost of all topics treated of in the scriptures. Righteousness has conduct for its basis. The unfading Vasudeva is said to be the Lord of righteousness. The Rishis, the Pitris, the deities, the great (primal) elements, the metals, indeed, the entire mobile and immobile universe, has sprung from Narayana. Yoga, the Sankhya Philosophy, knowledge, all mechanical arts, the Vedas, the diverse scriptures, and all learning, have sprung from Janardana. Vishnu is the one great element or substance which has spread itself out into multifarious forms. Covering the three worlds, He the soul of all things, enjoys them all."
His glory knows no diminution, and He it is that is the Enjoyer of the universe (as its Supreme Lord). This hymn in praise of the illustrious Vishnu composed by Vyasa, should be recited by that person who wishes to acquire happiness and that which is the highest benefit (viz., emancipation). Those persons that worship and adore the Lord of the universe, that deity who is inborn and possessed of blazing effulgence, who is the origin or cause of the universe, who knows no deterioration, and who is endued with eyes that are as large and beautiful as the petals of the lotus, have never to meet with any discomfiture."