The Thousand Names of Vishnu.
The Vishnu Sahasranāmam is found in the great epic Mahabharata, authored by the sage Veda Vyasa. 'Sahasra nāma' means thousand names, so this is a Sanskrit chant of thousand names of Lord Vishnu.
The names were handed down to Yudhisthira, by Bhishma, the great warrior, when he lay on his death bed at the battlefield of Kurukshetra. Yudhisthira had asked Bhishma:
In this universe who is the one Lord of all?
Who is the one refuge for all?
Who is the one Divinity by praising and by worshiping whom a man attains good?
Which is that highest form of Dharma?
What is that by uttering or reciting which any living being can attain freedom from cycle of births and deaths?
Bhisma answers by stating that mankind will be free from all sorrows by chanting the Vishnu Sahasranāma.
Here is MS Subbulakshmi reciting the Vishnu Sahasranāmam.
Prof Shivkumar Kalyanaraman's has provided a detailed explanation on the Vishnu Sahasranāmam here.
The 1000 Names are also available here.
Image: Vishwarupa (All-Encompassing Form).