Shay personified destiny, and existed both as a deity and a concept. In the New Kingdom funerary papyrus of the royal scribe Ani, Shay appears in the Weighing of the Heart scene as anthropomorphic. In the book of moral and religious precepts known as the Instruction of Amenemope, one passage stresses the futility of pursuing riches by pointing out that no one can ignore Shay, i.e. what is fated. The god, as a personification of the span of years, and prosperity that a person can expect to enjoy, comes out clearly in inscriptions from the reign of the heretic king, Akhenaten in the 18th Dynasty. Here, both the king and the god Aten are described as "the Shay who gives life".
The god frequently appears mentioned beside goddesses who have some affinity with his role, including Renenutet, Meskhenet and Shepset, a benign minor goddess worshipped mostly in Memphis. Shay coalesces in the Graeco-Roman period with Agathodaimon, the popular serpent god of fortune at Alexandria.