Vishnu Sahasranama Sthothram By Upanyasa Shiromani,Abhinava Vyasa Shri Kandadai Ramanujacharya Ep 152

The Vishnu Sahasranam is found in the Mahabharata. Literally translated this means thousand names of Vishnu. This is found in the Anushasanika Parvam (chapter relating to orders or rules to the kings) of Mahabharata.

Bheeshma Pitamaha was defeated and grievously wounded by Arjuna. But since he could choose the time of his death as per the boons received by him, he chose to die in Uttarayana and was waiting for the auspicious time. Meanwhile the war was over leading to death of all those male members in his family except the Pancha Pandavas and the unborn child of Abhimanyu. Yudishtira the eldest of the Pandavas became the King of Hasthinapura and whom else would he go for advise other than Bheeshma the great. Anushasanika Parva is in the form of questions and answers between Yudishtira and Bheeshma Pitamaha.To a question as to what is the best possible sthothra, Bheeshma answers that it is the Vishnu Sahasra Nama and teaches it to Yudishtira.