Jamieson, Fausset and Brown on Leviticus 17:7

7. they shall no more offer their sacrifices unto devils--literally, "goats." The prohibition evidently alludes to the worship of the hirei-footed kind, such as Pan, Faunus, and Saturn, whose recognized symbol was a goat. This was a form of idolatry enthusiastically practised by the Egyptians, particularly in the nome or province of Mendes. Pan was supposed especially to preside over mountainous and desert regions, and it was while they were in the wilderness that the Israelites seem to have been powerfully influenced by a feeling to propitiate this idol. Moreover, the ceremonies observed in this idolatrous worship were extremely licentious and obscene, and the gross impurity of the rites gives great point and significance to the expression of Moses, "they have gone a-whoring."