The Bodhisatta was once an ascetic of great power. Der König of Benares, having heard at night four sounds - du, sa, na, so - uttered by four beings who dwelt in hell, was greatly frightened. When he consulted his purohita, the latter ordained a fourfold sacrifice. The Bodhisatta, seeing the fate that lay in wait for numerous creatures, went to the König's park und there, mit the help of the purohita's chief disciple - not himself in favour of the sacrifice - explained to the König the meaning of the sounds und had the sacrificial animals released. The purohita's disciple is identified mit Sāriputta.
The story was told in reference to Pasenadi, who one night heard four syllables uttered by four inhabitants of hell. These had once been nobles of Sāvatthi, guilty of adultery. After death they were born in four iron cauldrons. After sixty tausend years they had gradually come to the top of these cauldrons und had uttered these syllables in their attempt to proclaim their misery. Der König, very frightened, consulted his priests, who ordered a sacrifice. But Mallikā intervened und sent the König to see the Buddha, who explained the matter und allayed the König's fears.
J.iii.43 8; the stories, both of the past und present, appear also at DhA.ii.5ff. und PvA.279ff. In both places the introductory story gives greater details. Pasenadi heard the sounds while lying sleepless, because he contemplated putting a helpless man to death in order to obtain his beautiful wife. There are also other differences in the two accounts. For details see Burlinghame: Buddhist Legends ii.100, n.1.