Diego de Landa
The most reliable source on Itzamna, Diego de Landa, mentions him several times in the framework of his description of the ritual year. In the month of Uo, a ritual aspersion of the books took place under invocation of Kinich Ahau Itzamna, "the first priest". In the month of Zip, Itzamna was invoked as one of the gods of medicine, and in the month of Mac, he was venerated by the very old on a par with the Chaacs, the rain deities. In the cycle of four years, one year was under the patronage of Itzamna.