What is Onaah and how does the Torah define it?

Onaah (from the root a-n-h, to oppress or wrong) refers to price fraud in commercial transactions: charging significantly more than the fair market price (overcharging) or accepting significantly less (underpricing). The Talmud (Bava Metzia 50b) worked out specific thresholds: a discrepancy of up to one-sixth of the fair price is tolerated; more than one-sixth constitutes Onaah and the aggrieved party may cancel the transaction. The prohibition applies symmetrically to buyer and seller — Lev 25:14 says “if thou sell” and “if thou buy,” covering both directions of fraud.

Does Onaah apply when the overcharged party knows the price?

Generally no: if the buyer or seller knows the true market price and agrees to the transaction anyway, they have waived the Onaah claim. Disclosure of the price discrepancy — “I know this costs X in the market, but I am charging you Y” — also removes the Onaah. The prohibition targets hidden fraud, not disclosed premium transactions. However, creating a false impression of the price even without explicit lies — for example, presenting inflated comparable sales to justify a price — is covered under the related prohibition of geneivat da'at (commandment #355).

What is "Onaah of words" and how does it differ from financial Onaah?

Leviticus 25:17 states: “Ye shall not oppress one another.” The rabbis distinguish this from v.14's financial Onaah by deriving a prohibition on verbal oppression from v.17. Ona'at devarim covers: reminding a penitent of their past sins, asking a scholar a question you know will embarrass them, suggesting to a buyer that they look at your merchandise when you know they cannot afford it, pointing out defects in a completed purchase when nothing can be done. The Talmud (Bava Metzia 58b) states that verbal Onaah is worse than financial Onaah — financial harm can be repaired by paying back money; wounds to a person's dignity cannot be repaid.

What did Amos say about commercial fraud and Sabbath observance?

Amos 8:4–6: “Hear this, O ye that swallow up the needy, even to make the poor of the land to fail, Saying, When will the new moon be gone, that we may sell corn? and the sabbath, that we may set forth wheat, making the ephah small, and the shekel great, and falsifying the balances by deceit? That we may buy the poor for silver, and the needy for a pair of shoes; yea, and sell the refuse of the wheat.” The merchants Amos confronted were outwardly keeping Shabbat and new moon — but internally counting the hours until they could return to false scales. Their religion was a pause in their fraud, not an alternative to it. Amos saw through the calendar observance to the heart that was already planning the next deceptive transaction.

Commandment #352 · Negative · Commerce Ethics · Neighbor Dignity

Do Not Commit Price Fraud (Onaah)

לֹא לִרְמֹת

Source: Leviticus 25:14 · Maimonides, Sefer HaMitzvot, Negative #601

וְכִי תִמְכְּרוּ מִמְכָּר לַעֲמִיתֶךָ אוֹ קָנֹה מִיַּד עֲמִיתֶךָ אַל תּוֹנוּ אִישׁ אֶת אָחִיו

“And if thou sell ought unto thy neighbour, or buyest ought of thy neighbour's hand, ye shall not oppress one another.”

Leviticus 25:14 — Open in Reader

Onaah — The Unequal Transaction

Leviticus 25:14: “And if thou sell ought unto thy neighbour, or buyest ought of thy neighbour's hand, ye shall not oppress one another.” The verse covers both directions of commerce: the seller who overcharges and the buyer who underpays. Onaah is not limited to fraud by the powerful against the weak — both parties in a transaction carry the obligation to deal at fair prices. The word “al tonu” (do not oppress) uses the same root as the oppression of the stranger (Exodus 22:21) and the widow (Exodus 22:22) — the Torah treats commercial price fraud as a form of oppression, not merely a business ethics violation.

The Talmudic elaboration of Onaah in Bava Metzia 50a–51b develops precise thresholds: a price discrepancy of less than one-sixth of market value is considered negligible and forgiven; exactly one-sixth allows the aggrieved party to demand the difference; more than one-sixth allows full cancellation of the transaction. These thresholds reflect a recognition that perfect price information does not exist — some variance is inevitable — while still providing a mechanism to address significant fraud.

Onaah of Words — The Damage That Cannot Be Repaid

Leviticus 25:17: “Ye shall not oppress one another: but thou shalt fear thy God: for I am the LORD your God.” The rabbis read this verse as addressing verbal oppression — distinct from the financial Onaah of v.14. The common element: both forms produce damage in the other person. Financial Onaah produces monetary damage. Verbal Onaah produces damage to dignity, self-perception, and standing that cannot be compensated with money.

The Talmud's examples of verbal Onaah (Bava Metzia 58b) are precise: do not tell a penitent to remember their old ways; do not ask a scholar a question about a subject in which they are ignorant; do not ask a merchant the price of something you are not intending to buy (creating false hope of a sale). Each example involves using the other person's vulnerability — their past, their gaps, their need for business — as an opportunity to produce shame. The connecting principle: verbal Onaah exploits knowledge of the other person's sensitive places. Financial Onaah exploits ignorance of the market price. Both are forms of using the other person's position against them.

Amos and the False Balances

Amos 8:4–6 is the prophetic articulation of commandment #352 violated at scale. The merchants of the northern kingdom were observed outwardly: they kept Shabbat and new moon (the religious calendar was maintained). But the prophet sees through the calendar observance to the heart: “When will the new moon be gone, that we may sell corn? and the sabbath, that we may set forth wheat, making the ephah small, and the shekel great, and falsifying the balances by deceit?”

The specific violations: making the ephah small (underweighting the goods sold), making the shekel great (overweighting the price paid in silver), and falsifying the balances (rigging the scale itself). These are three separate mechanisms of Onaah — fraud in quantity, fraud in payment, and fraud in measurement. Amos concludes the indictment: “That we may buy the poor for silver, and the needy for a pair of shoes; yea, and sell the refuse of the wheat.” The commercial fraud was not petty — it was systematic enough to reduce the poor to debt servitude. Commandment #352's violation is not a victimless overcharge; it is the mechanism by which the vulnerable are consumed.

Amos — The shepherd-prophet who confronted the northern kingdom's market fraud in Amos 8. His indictment names three specific forms of commercial Onaah — false ephah, false shekel, falsified balances — and traces their cumulative effect: the poor reduced to debt slavery.
The Merchants of Amos 8 — The paradigmatic violators of commandment #352: they kept Shabbat and new moon outwardly while planning commercial fraud the moment each ended. Their religion was a pause in their fraud, not a transformation of their commercial practice.
The Aggrieved Party — Leviticus 25:14's provision: the party who suffered Onaah has legal recourse. The Torah does not merely prohibit the fraud — it creates a mechanism for its reversal. Onaah is not just a sin; it is a remediable wrong.

For reflection and group study

Onaah applies symmetrically to buyer and seller — both overcharging and underpricing are prohibited. Why would the Torah prohibit a seller from accepting too little for their goods? Who is harmed when a transaction prices too low? What does this symmetry reveal about the Torah's understanding of fair exchange?

See Leviticus 25:14 — Open in Reader

Amos observed merchants who maintained outward Sabbath observance while mentally planning the next morning's commercial fraud. The external religion was real; the internal commerce was unchanged. What does Amos's confrontation reveal about the relationship between ritual observance and commercial ethics in the covenant? Can they be genuinely separated?

See Leviticus 25:14 — Open in Reader

Read the source passage in the Torah reader.

Read in the Torah Reader — Leviticus 25:14

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