On one occasion a plague spread in the city Vesali and many inhabitants died. At that time Gotama Buddha, staying in Rajagaha, was asked by an envoy from Vesali to come, and went there. On his crossing the Ganga people and gods held many sunshades over him to honour him. As he arrived in the city and uttered the Ratanasutta, the plague subsided.
This legend is found in several texts such as the Commentary to the Dhammapada, Mahavastu, and Vinaya of the Mulasarvastivadin and so on. These Recensions of this legend have many differences in details, but agree on the next point; Gotama Buddha stayed in Rajagaha with the aim of spending the rainy season there. From the context one can suppose, that, because Gotama Buddha refused to spend the rains retreat in Rajagaha and went to Vesali, he should have spent the rainy season there. Nonetheless no recension mentions it.
The Commentary to the Anguttaranikaya and other later commentarial works give us the locations of Gotama Buddha's rains retreats in the form of a list. According to it, the city Vesali is where the Gotama Buddha spent his fifth rains retreat. Did the commentators intend that the event told in this legend occured in the fifth year? The writer inquires into the appropriateness of this hypothesis in this paper.