Kabbalah do Estery 2:9

And Come and behold, From that river, the seven grades are watered and blessed by it. These are "well favored, and fat of flesh", who "fed in the reed grass." (That is), they fed together in friendship, and there was no separation among them. All of them stand to be praised, for these seven grades are the mystery of the verse, "and the seven maids chosen to be given her, out of the king's house" (Esther 2:9). And so are the "seven cows well favored," all to be praised. In contrast, "the seven chamberlains who served in the presence of the king" (Tehilim 1:10) are not to be wholly praised, for they include a portion of the powers of defilement, which is the secret of the seven lean cows.