Midrash su Deuteronomio 25:9

(Bamidbar 5:17) "And the Cohein shall take consecrated water: This refers to water consecrated in a vessel, the waters of the laver. "in an earthen vessel": We are hereby taught that all vessels are not equated with earthen vessels. For it would follow: Since soil and water consecrate in the instance of the red heifer and soil and water consecrate in the instance of sotah, then if I derive that all vessels are equated with earthen vessels re the red heifer, then re sotah, too, all vessels should be equated with earthen vessels; it is, therefore, written (specifically) "in an earthen vessel" (to negate the above derivation). "in an earthen vessel": a new one. For it would follow: If I have derived that re the red heifer both a new and an old vessel are permitted, I should derive the same for sotah. It is, therefore, written here "in an earthen vessel," and, elsewhere (Vayikra 14:5) "into an earthen vessel." Just as there, a new one, here, too, a new one. These are the words of R. Yishmael. "and of the soil that shall be on the floor of the mishkan the Cohein shall take": Scripture hereby teaches us that if there were no soil there, he brings soil from elsewhere and places it there; for it is the place which consecrates. Issi b. Yehudah says ("that shall be"): to include (the same for) the soil of the Temple (in Jerusalem). Issi b. Menachem says (in demurral): If in respect to a lesser form of tumah (e.g., dead-body tumah or sheretz tumah), the Temple (mikdash) was equated (vis-à-vis kareth liability for entry) with the sanctuary (mishkan), then, in respect to a graver form of tumah, sotah, (where death is the punishment,) how much more so, should the (strictures of the) mikdash be equated with (those of) the mishkan! Why, then, need it be written "that shall be on the floor of the mishkan"? — That he not bring soil in his basket, (but shall use soil that is already there.) R. Shimon says: It is written here "afar" ("and of the afar that is on the floor of the mishkan"), and, elsewhere (Ibid. 19:17) "And they shall take for the unclean one of the afar of the burning of the (heifer) for cleaning." Just as "afar" here," "afar on the face of the water" (i.e., visible on the surface of the water), so, there, afar on the face of the water. And, just as there if the afar preceded the water, it is valid, so, here. "the Cohein shall take (the afar) and place it on the water": so that it be visible. Three "things" in the Torah must be visible: the ashes of the heifer (Ibid.), the afar of the sotah, and the spittle of the yevamah (viz. Devarim 25:9). R. Yishmael says: Also the blood of the (slaughtered) bird (viz. Vayikra 14:6).

(Bamidbar 5:19) "And the Cohein shall beswear her": The Cohein administers the oath and she does not swear of herself. For it would follow (that she does), viz.: It is written here "swear," and, elsewhere (Vayikra 5:4) "swear." Just as there, he swears of himself, so, here, she should swear of herself. It is, therefore, written "And the Cohein shall beswear her." "and he shall say to the woman": in any language that she understands. These are the words of R. Yoshiyah. For it would follow (otherwise), viz.: If in the instance of yevamah, (the instance) of lesser stringency, the other languages are not equated with the holy tongue (Hebrew) (viz. Devarim 25:9), then, (in the instance of) sotah, the graver instance, how much more so should the other languages not be equated with the holy tongue! It is, therefore, written "and he shall say to the woman" — in any language that she understands. These are the words of R. Yoshiyah. R. Yonathan says: This (derivation of R. Yoshiyah) is not necessary; for it is written (Bamidbar 5:22) "and the woman shall say 'Amen,' 'Amen.'" If she does not understand, how can she say this! — But perhaps she says "Amen" only on the curse (i.e., "to swell the belly, etc." [and not on the oath])! — (This cannot be,) for she says Amen twice — both on the curse and on the oath. What, then, is the intent of "and he shall say to the women" (according to R. Yonathan)? That the Cohein teaches her (the import of) the order of the oath. (5:19) "If no man has lain with you": We are hereby taught that he opens for merit. He says to her: Much wine causes this. Much frivolity causes this. Much childishness causes this. Many have preceded you and been swept away (by lust). Do not allow His great name written in holiness to be erased by the (bitter) waters. He recounts before her things from the tradition, things mentioned in the early writings (Iyyov 15:18) "which wise men relate and which they did not withhold from their fathers." And he says before her things which are not fit to be heard, by her and by all the families of her father's house. R. Yishmael says: In the beginning he apprises her of the strength of the bitter waters. He says to her: My daughter, what are these bitter waters like? Like a dry powder placed on raw flesh, which causes no harm, but which, when it finds a sore spot, penetrates and descends. You, too, if you are clean, drink and do not refrain, and, if you are unclean, in the end you will be swollen by these bitter, blighting waters.

The Holy One, blessed be He, declared unto him: Inasmuch as you have said: “I will not take a thread,” I shall absolve your sons of the sins they commit at the altar around which a crimson thread will be encircled. As we have learned, the altar was encircled with a crimson thread. Furthermore, in reward for declaring: “I will not take a thread,” I will give your sons the precept of the purple fringes (on their prayer shawls). And since you said: “Nor a shoe-latchet,” I will give thy children the precepts of yebamah and halitzah: And loose his shoe from off his foot (Deut. 25:9).²²Yebamah is the law requiring a brother to marry his deceased brother’s wife when there has been no issue. Halitzah is the ceremony of throwing a shoe at the brother-in-law which releases him from marrying the widow. In reward for saying: “Nor a shoe-latchet,” I will issue your sons the decree to eat the paschal lamb, of which it is written: And thus shall ye eat it; with your loins girded, your shoes on your feet … it is the Lord’s passover (Exod. 12:11). Furthermore, I will exact retribution from Esau through it, as it is said: Upon Edom do I cast my shoe (Ps. 60:10). Likewise, I shall praise your children with that word, as it is said: How beautiful are thy steps in shoes (Song 7:2). Since you rejected the reward sought by ordinary men, your reward shall be multiplied in this world and in the world-to-come.