Flavius Josephus, The Wars of the Jews
William Whiston, A.M., Ed.

[128] And as for their piety towards God, it is very extraordinary; for before sun-rising they speak not a word about profane matters, but put up certain prayers which they have received from their forefathers, as if they made a supplication for its rising. After this every one of them are sent away by their curators, to exercise some of those arts wherein they are skilled, in which they labor with great diligence till the fifth hour. After which they assemble themselves together again into one place; and when they have clothed themselves in white veils, they then bathe their bodies in cold water. And after this purification is over, they every one meet together in an apartment of their own, into which it is not permitted to any of another sect to enter; while they go, after a pure manner, into the dining-room, as into a certain holy temple, and quietly set themselves down; upon which the baker lays them loaves in order; the cook also brings a single plate of one sort of food, and sets it before every one of them; but a priest says grace before meat; and it is unlawful for any one to taste of the food before grace be said. The same priest, when he hath dined, says grace again after meat; and when they begin, and when they end, they praise God, as he that bestows their food upon them; after which they lay aside their [white] garments, and betake themselves to their labors again till the evening; then they return home to supper, after the same manner; and if there be any strangers there, they sit down with them. Nor is there ever any clamor or disturbance to pollute their house, but they give every one leave to speak in their turn; which silence thus kept in their house appears to foreigners like some tremendous mystery; the cause of which is that perpetual sobriety they exercise, and the same settled measure of meat and drink that is allotted them, and that such as is abundantly sufficient for them.