This is an excerpt from Josephus’ “Jewish Antiquities”, finished in Rome around the year 93/94 CE. Here, Josephus, a Jewish aristocrat describes a legend that explains why Herod had such favor towards the Essenes. Apparently it was on the account of the prophecy of his kingdom because Menahem the Essene had foreknowledge from God himself.
(373) Now there was one of these Essenes, whose name was Manahem, who had this testimony, that he not only conducted his life after an excellent manner but had the foreknowledge of future events given him by God also. This man once saw Herod when he was a child, and going to school, and saluted him as king of the Jews; (374) but he, thinking that either he did not know him, or that he was in jest, put him in mind that he was but a private man; but Manahem smiled to himself, and clapped him on his backside with his hand, and said, “However that be, thou wilt be king, and wilt begin thy reign happily, for God finds thee worthy of it; and do thou remember the blows that Manahem hath given thee, as being a signal of the change of thy fortune; (375) and truly this will be the best reasoning for thee, that thou love justice [towards men], and piety towards God, and clemency towards thy citizens; yet do I know how thy whole conduct will be, that thou wilt not be such a one,
(376) for thou wilt excel all men in happiness, and obtain an everlasting reputation, but wilt forget piety and righteousness; and these crimes will not be concealed from God at the conclusion of thy life, when thou wilt find that he will be mindful of them, and punish thee for them.” (377) Now at that time Herod did not at all attend to what Manahem said, as having no hopes of such advancement; but a little afterward, when he was so fortunate as to be advanced to the dignity of king, and was in the height of his dominion, he sent for Manahem, and asked him how long he should reign. (378) Manahem did not tell him the full length of his reign; wherefore, upon that silence of his, he asked him further, whether he should reign ten years or not? He replied, “Yes, twenty, nay, thirty years;” but did not assign the just determinate limit of his reign. Herod was satisfied with these replies, and gave Manahem his hand, and dismissed him; and from that time he continued to honor all the Essenes. (Josephus, Antiquities 15. 373-378, Whiston Translation)