[The "Maha-Ummagga Jataka" is extraordinarily long in comparison to most of the other Jataka stories, nearly 47,000 words and over 70 pages in the English translation of E.B. Cowell and W.H.D. Rouse. What I have given you here is my paraphrase of the "frame story" as well as selections illustrating the many instances of the wisdom of the Buddha-to-be in a previous life.]
One day the Buddha's followers were sitting around marveling at the Master's "perfection of knowledge." The Teacher entered and, when he heard the topic, said, "Not only am I now omniscient, but even before my knowledge ripened I was possessed of great wisdom in many of my previous lives." He then told this story.