Midrash sobre II Samuel 13:19

(Bamidbar 5:18) "And the Cohein shall stand the woman before the L-rd": Where he stood her before (viz. Ibid. 16), he stands her afterwards, (after she had been moved away from her original position [They would walk her from place to place to "weary" her into confession]). "And he shall uncover the head of the woman": The Cohein moves behind her and uncovers her hair to fulfill the mitzvah to do so. R. Yishmael said: From here (i.e., from the fact that he is to uncover her hair) we derive an exhortation for the daughters of Israel to cover their hair. And though there is no proof for this, there is an intimation of it in (II Samuel 13:19) "And Tamar put earth upon her head … and she put her hand on her head." R. Yehudah says: If her top-knot were beautiful, he did not expose it, and if her hair were beautiful, he did not dishevel it. If she were dressed in white, she is dressed in black. If black were becoming to her, she is divested of it and clothed in ungainly garments. If there were golden ornaments upon her — necklaces, nose-rings, and rings — they are taken from her to render her unattractive. R. Yochanan b. Beroka says: The daughters of Israel are not made more unattractive than the Torah prescribes, viz. — "… before the L-rd and he shall uncover the head of the woman." They would spread a sheet of linen between him and the people. The Cohein would walk around her in order to fulfill the mitzvah of disheveling her hair. They say to him: Just as she was not solicitous of the honor of the L-rd, so, we are not solicitous of her honor — wherefore she is demeaned in this manner. And all who wish to look at her may do so except her man-servants and her maid-servants, for she is callous in their presence. Both men and women, kin and non-kin, may look at her, as it is written (Ezekiel 23:48) "and all the women will be chastised and not act according to your lewdness." (Devarim, Ibid.) "and he shall place into her hands the offering of memorial" Abba Channan says in the name of R. Eliezer: So that she is "wearied" into confession. Now does this not follow a fortiori, viz.: If the L-rd is so solicitous of the transgressors of His will, how much more so, of the doers of His will! "and in the hand of the Cohein will be the bitter waters": Scripture herby apprises us that the waters turn bitter only in the hand of the Cohein. Variantly: They are called "bitter" because of their effect — they impart bitterness to the body and convulse the eye.