Kojiki 86

Section LXXXVI. Emperor Kei-kō (Part XI.—Yamato-take Dwells in the Palace of Sakawori)

When, forthwith crossing over from that land out into Kahi, he dwelt in the palace of Sakawori, he sang, saying: “How many nights have I slept since passing Nihibari and Tsukuha?”

Then the old man, who was the lighter of the august fire, completed the august Song, and sang, saying: “Oh! having put the days in a row, there are of nights nine nights, and of days ten days!”

Therefore [Yamato-take] praised the old man, and forthwith bestowed [on him] the Rulership of the Eastern Land[s].