Hisba is the most double-edged obligation in Islam. Historically it was an office: the muhtasib policed weights, prices, and public order in the market, and the job was administrative rather than inquisitorial. The hadith of the three stages — hand, tongue, heart — is the text everyone quotes, and the classical commentary on it is far more restrictive than its modern use, requiring knowledge of the ruling, certainty about the facts, a reasonable expectation of success, and the absence of greater harm. Al-Ghazali added that a person who cannot correct without causing a riot must not correct. The modern problem is that the clause has been detached from authority and from those conditions by vigilante groups and by armed movements, and the mainstream Muslim response has been unusually direct: the Amman Message of 2005 restricted who may issue a fatwa at all, and the 2014 Open Letter to Baghdadi, signed by more than a hundred and twenty senior scholars, refuted the Islamic State point by point in its own juristic language.