The scene of unfolding this great Sahasranama happened in the great epic Mahabharata authored by sage, Veda Vyasa. Bhisma was lying on a bed made of arrows awaiting his death. At that time, he was meditating on Krishna. Knowing this, Krishna asked Yudhishthira (eldest among Pandava brothers and known for his righteousness) to seek spiritual initiation from Bhisma and also told Bhisma to initiate Yudhishthira. Yudhishthira asks Bhisma kimekam daivatam loke meaning who is the Supreme Lord of the world. Bhisma replies by saying, that the purest, the most auspicious, the chief among the gods and the father of all the beings is the One who is Supreme, referring to Lord Vishnu. This conversation appears in the prrvabhag of this Sahasranama. The spiritual initiation of Yudhishthira by Bhisma is Vishnu Sahasranama. Krishna was also present when this happened and this Sahasranama was blessed by the Lord Himself.
Vishnu is also known as Narayana. Garuda Purana (III.24.54, 55) explains the etymological meaning of Narayana. “As He is the resort of merits and demerits and as He abides in the waters of ocean, He is called Narayana. Water is also called nara (probably meaning cosmic water); as His Abode is water, He is called Narayana.” Vishnu is the most auspicious form of the Brahman. He is not only invoked during auspicious occasions, but also while performing funeral rites. At the time of conclusion of all rituals, the effect of the rituals are surrendered to Vishnu.
Vishnu Sahasranama consists of three parts – purvabhag or the first part; stotrabhag or the main part from which one thousand names or nama-s are composed; and uttarabhag or the concluding part. The main part consists of 108 couplets from which all the 1000 nama-s are derived. Apart from these three parts, this Sahasranama has seven dhyana verses by which one can meditate upon His auspicious form.
All the one thousand nama-s have been interpreted based on ancient Scriptures like Upanishad-s. Wherever possible, quantitation from Upanishad-s and other Scriptures have been used. Many of the nama-s are interpreted from the point of view of attaining Him to get liberation. Wherever needed, Sanskrit verses have been used along with IAST, for the sake of proper pronunciation.