Tacitus, Histories 5.4
To establish his influence over this people for all time, Moses introduced new religious practices, quite opposed to those of all other religions. The Jews regard as profane all that we hold sacred; on the other hand, they permit all that we abhor. They dedicated, in a shrine, a statue of that creature whose guidance enabled them to put an end to their wandering and thirst,9 sacrificing a ram, apparently in derision of Ammon.10 They likewise offer the ox, because the Egyptians worship Apis. They abstain from pork, in recollection of a plague, for the scab to which this animal is subject once afflicted them. By frequent fasts even now they bear witness to the long hunger with which they were once distressed, and the unleavened Jewish bread is still employed in memory of the haste with which they seized the grain.11 They say that they first chose to rest on the seventh day because that day ended their toils; but after a time they were led by the charms of indolence to give over the seventh year as well to inactivity.12 Others say that this is done in honour of Saturn,13 whether it be that the primitive elements of their religion were given by the Idaeans, who, according to tradition, were expelled with Saturn and became the founders of the Jewish race, or is due to the fact that, of the seven planets that rule the fortunes of mankind, Saturn moves in the highest orbit and has the greatest potency; and that many of the heavenly bodies traverse their paths and courses in multiples of seven.