Numbers 5:15

flour. But not of fine flour.

Barley. But not wheat. [Because] she acted like an animal, her offering consists of animal feed.

He shall not pour oil over it. So that her offering may not be resplendent. for, [olive] oil is identified as light, while she acted in darkness.

He shall not put frankincense on it. The matriarchs are called “frankincense,” as it is said, “. . . and to the hill of frankincense,” but she departed from their ways.

For it is a meal-offering of jealousy. This meal. “Meal” is masculine.

A meal-offering of jealousy (wrath). She arouses a double wrath against her; the wrath of the Supreme Omnipresent Being, and the wrath of her husband.

and though that man may have not brought separation or tythe, there is constraint upon him to bring his wife unto the priest. Now, because she may have brought delicacies to the adulterer, she ought to bring an appointed oblation of her own, a tenth of three sata of barley flour, that being the food of beasts: he shall not pour oil, nor put frankincense thereon; for it is a mincha (on account) of jealousy, a mincha of a memorial which calleth guilt to mind.

HE SHALL POUR NO OIL UPON IT — “so that her offering shall not be enriched, for oil is called light, whereas she acted in darkness. NOR SHALL HE PUT FRANKINCENSE THEREON, for the matriarchs are compared to frankincense, as it is said, to the hill of frankincense [an allegorical expression explained by the Midrash as an allusion to the matriarchs], but this woman turned aside from their [virtuous] ways (Midrash Tanhuma Nasso 3). FOR IT IS A MEAL-OFFERING OF JEALOUSIES. This flour arouses against her two jealousies — the jealousy of G-d, and the jealousy of her husband.” Thus far is Rashi’s language on the basis of the words of our Rabbis. 3; Sifre Naso 8.
But in the opinion of all the commentators [the meaning of the expression] for it is a meal-offering of jealousies is to say that because this meal-offering [of the sotah] is a woman suspected of adultery, and is subject to the laws explained further on in Verses 11-31. The law concerning her meal-offering is found in Verse 15, where it is called a meal-offering of jealousy. is an offering which may bring her punishment [if the charge against her is true], therefore it is of a lesser quality [than all other meal-offerings and is to be brought of] barley without oil and frankincense. On the other hand, a meal-offering of which the memorial-part is brought to be acceptable before the Eternal, is to be brought from fine wheat-flour with oil and frankincense. But in my opinion the expression for it is a meal-offering of jealousies refers to the beginning of the verse, stating that the husband shall bring the offering for his wife, that is to say, instead of her, for it is a meal-offering of jealousies bringing her iniquity to remembrance. Thus it is not fitting that she should bring it of her own property, but it is he who is to bring the meal-offering to G-d so that He should take note of his suspicions of her, and punish her on his [the husband’s] behalf. And the reason [why this meal-offering comes from] se’orim (barley) (barley) is suggestive of the word sa’ar (storm), as is indicated in the next verse quoted by Ramban. is so that ‘sa’arath’ (a storm of) the Eternal is gone forth in fury, yea, a whirling storm; it shall whirl upon the head of wickedness, like the cake of barley bread, 22-28). mentioned in the story of Gideon, which [one of the Midianites who saw it in a dream] interpreted as …

והביא האיש את אשתו, we do not say that seeing that her husband had sat by silently while his wife had behaved unchastely, accusing her in his heart without saying a word, that this is proof of the husband’s bad attitude and we should therefore ignore his jealousy seeing he had allowed matters to get to the point where she had slept with another man; neither do we ignore his jealousy if she had not given him cause as something not worth paying attention to. We still subject her to the destruction (erasing) of the name of G’d (in the procedure the Torah will presently describe) in order to reveal the truth.

מזכרת עון, “as a reminder of an iniquity committed.” Other types of meal offerings are described as לכפר עון, “to atone for an iniquity committed.” We know of a מנחת חוטא “meal offering of a sinner;” מנחת נדבה “a voluntary meal offering;” these meal offerings are accompanied by oil and לבונה, frankincense, in order for that offering resulting in a pleasant fragrance, ריח ניחוח, in order to remind the Lord of the merits of the donor. Seeing that the mandatory offering discussed here is not intended to remind G–d of the donor’s merits but her husband brings his wife to the priest as an accuser, the offering only serves as a reminder of his sin. [It is not clear yet at this point if the wife was guilty of serious misconduct. Ed.] (Compare Talmud, tractate Sotah, folio 15)