The Mahabharata in Anusasana Parva 13.135 has the most authoritative version authored by Rishi Veda Vayāsa. Other Puranas such as Padam Purana, Sakandha Purana, and Garuda Purana also have versions of it. Sundar Gutakā has version of it by Guru Gobind Singh ji. Hari Ananta… Hari kathā anantā….

The context is this: Yudhisthra asks Sri Krishna about the ultimate import of Dharma and how to be free from the bondage of Samsāra. Sri Krishna takes him to the place where Bhishma is laid on the sarasaiyā (bed of arrows). Sri Krishna tells Yudhisthra that he should seek answer regarding all such questions about Dharma from Bhishma, as he is the reservoir of the essence of Dharma (notice the subtle point here: Sri Krishna did not answer directly, as he did to Arjuna in the Bhagavad Gītā, but directs him to a competent teacher—true to His own teaching in BG 4.34).

Then, Yudhisthra asks 6 questions to Bhishma about Dharma:

युधिष्ठिर उवाच —

किमेकं दैवतं लोके किं वाप्येकं परायणम् ।

स्तुवन्तः कं कमर्चन्तः प्राप्नुयुर्मानवाः शुभम् | ८॥

को धर्मः सर्वधर्माणां भवतः परमो मतः ।

किं जपन्मुच्यते जन्तुर्जन्मसंसारबन्धनात् |९॥

1.⁠ ⁠Kim ekam devatam loke? Who is the greatest Lord in the world?

2.⁠ ⁠⁠Who is the one refuge (paraayanam) for all?

3.⁠ ⁠⁠By glorifying (sthuvantah) whom can man (maanavah) reach shubham (auspicousness)

4.⁠ ⁠By worshiping whom can a man reach shubham?⁠

5.⁠ ⁠⁠Ko dharmah sarva dharmANaam bhavatah paramO mataha? – What is, in your opinion, the greatest Dharma?

6.⁠ ⁠⁠⁠Kim japam muchyate jantur janma samsara bandhanath? – By doing what japa, can a creature go beyond the samsāric bondage of the cycle of births and deaths?

After mentioning that Lord Narayana (Shri Hari) as the one and only one Supreme Lord and Nama Sankirtana (chanting holy names) as the best of the means, Bhishma gave us all the 1000 holy names of Lord Vishnu in the form of Vishnu Sahasranama (VS).

One more thing to bear in mind about it is that VS is recited in the very presence of Sri Krishna. Bhagvān Sri Krishna is the sākshī of it.

This is the point of narrating the context above.‎

This recitation of Vishnu Sahasranama by M. S. Subbulakshmi is the best:

https://www.youtube.com/watch?v=ATflA6WOy0I

Hairh Om!