River Osun takes its source from Igede-Ekiti, meanders through Ilesha and the grove in Osogbo. The water goddess Osun established her kingdom there, assisted by lesser spirits to carry out her daily routine, which included dyeing.
Between the 16th and 17th centuries when Oba Laroye (a.k.a Gbadewolu), the Owa Oroki of Ipole Omu, Olutinmehin (a great hunter) and their subjects migrated from Ipole Omu because of scarcity of water, they also settled at the grove.
One day, as they were preparing the ground for the planting season, a tree fell across the river, crushing many of Osun's tools of trade. It is recorded that the goddess was at her wit's end: "Laroye, Olutimehin, gbogbo ikoko aro mi le ti fo tan (you've destroyed all my dyeing pots)," she cried.
The lesser spirits within the grove pacified the goddess, saying: "Oso igbo pele o. Oso igbo ro ra o." (Literal meaning: ‘Spirit of the forest, we plead. Spirit of the forest, be patient.'). Laroye and Olutimehin were shocked, because they didn't know how the goddess got to know their names.
She sensed this, and later advised them to move to the upper parts of the river (called Ohun toto) to domicile. There, Oba Laroye established another palace as well as a thriving market.
One day, on an expedition, Olutimehin saw spirits dancing round a lamp with 16 receptacles, which he seized. When the goddess learnt of this, she made Olutimehin and Laroye promise to celebrate the lighting of the lamp annually, particularly when the grand finale of the Osun festival is nine days away.
She gave them a calabash containing antiquities with a warning that the contents must never be exposed to the naked eyes. She also decreed that the calabash in question must be taken to the grove during the festival by a virgin with filial ties to the reigning king, and who must be chosen by the Ifa oracle.
On festival day, the kabiyesi (king) sits on a dedicated stone of authority housed in the Osun temple/shrine where he communes with the ancestors. Osun promised that if her instructions are carried out, she would pour a curative substance into the river as soon as she accepts the sacrifice from the Ataoja.