Abstract
This article examines the ḥadīth of Ibn Masʿūd (may Allah be pleased with him) declaring the cursing of a believer to be fusūq and the fighting of him to be kufr. Through analysis of the report’s two clauses, its scholarly interpretation, and the wider Qurʾānic framework in which it sits, the paper sets out the ethical framework it establishes: the twin obligations of purity of the tongue (ʿiffat al-lisān) and purity of the hand (ʿiffat al-yad), and the supreme sanctity these safeguard.
Introduction
A foundational text in Islamic interpersonal ethics is the ḥadīth of Ibn Masʿūd (may Allah be pleased with him), agreed upon by al-Bukhārī and Muslim. In it the Prophet ﷺ addresses two distinct modes of harm — the verbal and the physical — and assigns to each a grave designation. The tradition thereby establishes the paramount importance of safeguarding both the psychological and the physical wellbeing of the individual within the community, and yields two defining marks of the true believer: purity of the tongue and purity of the hand.
The Text (Matn)
«سِبَابُ الْمُسْلِمِ فُسُوقٌ، وَقِتَالُهُ كُفْرٌ»
“Cursing a Muslim is fusūq (grave transgression), and fighting him is kufr (disbelief).”
Grading (Ḥukm)
Ṣaḥīḥ, muttafaq ʿalayh — agreed upon, recorded by both al-Bukhārī and Muslim, and thus of the highest rank of authenticity.
Purity of the Tongue: The Prohibition of Verbal Abuse (Fusūq)
The first clause addresses cursing, insulting, and verbal abuse directed at a Muslim. In the ethical and juristic reading, this encompasses any damaging rhetoric: foul language, degrading comparisons to animals, and shaming a person for physical or character defects. The prohibition holds regardless of the origin of the dispute — whether it arises from worldly conflict or from religious disagreement, the tongue remains bound.
The narrow exception, and the better course. Scholars note a limited allowance under the parameters of equal retaliation (qiṣāṣ), and only where the other party initiated the abuse — the response may not exceed what was received. Yet the sources are emphatic that forgoing retaliation and entrusting the matter to Allah is the morally superior choice, and the one more befitting the believer’s station.
The exemplar. The supreme model of this purity is the Prophet ﷺ himself, who abstained from foul speech, insult, and vulgarity, maintaining measured and gentle discourse even with his adversaries. Believers are accordingly commanded to hold to that standard consistently — with the public, with their companions, and no less within their own households, where speech is most easily let loose.
Purity of the Hand: The Prohibition of Violence (Kufr)
The second clause addresses fighting a Muslim. The unlawful taking of a Muslim’s life ranks among the gravest of the major sins (akbar al-kabāʾir). Its severity is underscored in Sūrat al-Nisāʾ (4:93), which decrees for one who kills a believer intentionally a recompense of Hell, abiding therein, together with Allah’s wrath, His curse, and a mighty punishment.
The theological nuance of “kufr.” Although the ḥadīth designates fighting a believer as kufr, the scholars supply an essential qualification: the term here denotes minor disbelief (kufr aṣghar) — an enormity of the gravest kind, but one that does not expel the transgressor from the fold of Islam. This reading rests on Sūrat al-Ḥujurāt (49:9–10), which addresses two warring factions of Muslims and, even amid their armed conflict, continues to name both parties believers and brothers, commanding the community to reconcile between them. The Qurʾān thus preserves the faith of the combatants while condemning the combat, and the ḥadīth’s wording is to be understood in that light.
The Supreme Sanctity of the Believer
At the heart of the tradition lies the Islamic conception of the sanctity of human life and honour. The inviolability of the Muslim is declared greater even than the inviolability of the Sacred House itself. On account of this elevated standing, a believer’s life, wealth, and honour may not be violated absent clear legal and divine warrant.
This reverence functions as a distinguishing marker of orthodox faith. The people of sound belief are the most restrained regarding the shedding of blood, the most scrupulous in honouring covenants, and the furthest from treachery. Their conduct stands in stark contrast to that of deviant and extremist sects — the Khawārij foremost among them — and of the hypocrites, who are marked precisely by their trivialisation of Muslim life, wealth, and honour, and their readiness to violate all three.
Conclusion
The ḥadīth of Ibn Masʿūd furnishes a compact and comprehensive framework for relations between Muslims. By categorically condemning verbal abuse as fusūq and physical violence as kufr, the Prophet ﷺ established that authentic faith must show itself outwardly in disciplined self-restraint. Purity of the tongue and purity of the hand are therefore not optional refinements of character but constitutive traits of the believer — the outward evidence that the sanctity of one’s brother has been truly internalised.
And Allah knows best.