The Prophet (peace and blessings be upon him) forbade much swearing in dealing with one another in buying, selling, or other kinds of transactions. Taking many oaths is detestable if the person who swears is telling the truth, but if he or she is intentionally lying, then this is regarded as a prohibited action. Moreover, taking many oaths destroys blessings, so whoever swears many oaths should try to control his or her tongue and should give much in charity.
Dr. Husam al-Din ibn Musa `Afana, professor of principles of Islamic jurisprudence at Al-Quds University, Palestine, states: Taking many oaths is a sign of mistrust prevailing among people, which makes them resort to swearing in order to believe one another. Taking many oaths is detestable even if the person who swears is telling the truth. Allah Almighty says, (and keep your oaths) (Al-Ma’idah 5:89). Commenting on this verse, Al-Qurtubi says, “‘Keep your oaths’ means by giving up taking oaths, as when you stop taking oaths, the entailed obligations will not be binding to you.”
Al-Qurtubi also reported that some of the interpreters of the Qur’an commented on the verse (And make not Allah, by your oaths, a hindrance to your being righteous and observing your duty unto Him and making peace among mankind. Allah is Nearer, Knower) (Al-Baqarah 2:224) saying, “The meaning intended here is this: Do not take many oaths in Allah’s name, for He Almighty is worthy of being feared. That is why the Almighty says, (and keep your oaths), and for the same reason He dispraised those who are used to taking many oaths as saying, (Neither obey thou each feeble oath monger) (Al-Qalam 68:10). The Arabs used to praise anyone who is not used to taking many oaths” (Al-Qurtubi’s Tafseer of the Qur’an Vol. 3, p. 97).
On the other hand, if the person who swears is lying intentionally, then he or she is committing a great sin. The Almighty says, (Lo! Those who purchase a small gain at the cost of Allah’s covenant and their oaths, they have no portion in the Hereafter. Allah will neither speak to them nor look upon them on the Day of Resurrection, nor will He make them grow. Theirs will be a painful doom) (Aal `Imran 3:77).
The Prophet (peace and blessings be upon him) forbade much swearing in trade transactions such as selling and buying. In this concern, Abu Hurairah (may Allah be pleased with him) narrated: I heard the Prophet (peace and blessings be upon him) saying, “Swearing (by the seller) may persuade the buyer to purchase the goods, but it deprives of Allah’s blessing” (Al-Bukhari and Muslim). Abu Qatadah Al-Ansari (may Allah be pleased with him) also narrated that he heard the Prophet (peace and blessings be upon him) saying, “Beware of swearing; it produces a ready sale for the commodity, but then blots out the blessing” (Reported by Muslim). Commenting on this hadith, Imam An-Nawawi says, “The hadith indicates the forbiddance of much swearing in transactions, for unnecessary swearing is detestable, and by analogy, swearing to push the sale of a commodity is also detestable, for the buyer may be deceived” (An-Nawawi’s Sharh Sahih Muslim, Vol. 3, p. 220).
Al-Hafiz Abul-`Abbas Al-Qurtubi, the prominent scholar of Hadith and the exegete of the Qur’an, commented on the hadith: “Beware of swearing; it produces a ready sale for the commodity, but then blots out the blessing,” He says: “Blotting out the blessing means taking it away. Swearing may also take away the capital, as Allah says, (Allah hath blighted usury and made alms giving fruitful) (Al-Baqarah 2:276). This blight may also befall the swearer, as he might be punished by destruction and sufferance from successive misfortunes, or even the destruction of his home. It is reported that the Prophet (peace and blessings be upon him) said, ‘False swearing leaves homes wastelands,’ that is, empty of their dwellers who agreed to swear falsely.
As regards blotting out good deeds in the Hereafter, it is inevitable for the false swearers who have not repented, for a false oath is perjury committed for usurping a Muslim’s property with falsehood. In the hadith, ‘Beware of swearing; it produces a ready sale for the commodity, but then blots out the blessing,’ the word ‘beware’ indicates warning and prevention. The Prophet (peace and blessings be upon him) warns against much swearing because whoever does so becomes involved in much lying. If not, which is unlikely, he becomes involved in perjury or regret, and if not, he will definitely be involved in praising the good he is swearing about and exaggerating in its advantages so that the buyer
may purchase it. In doing so, the buyer will be mentioning Allah with the intention of glorifying the good, not Allah. These are all wrongdoings which no one attempts except the one with a corrupt mind and religion” (The abridgment of Sahih Muslim vol.4, pp.522-523).
Moreover, `Abdullah ibn Abi `Awfa (may Allah be pleased with him) narrated the following hadith: “A man displayed some goods in the market and swore by Allah that he had been offered so much for that, which amount was not offered, and he said so in order to cheat a Muslim. On that occasion the following verse was revealed: (Lo! Those who purchase a small gain at the cost of Allah’s covenant and their oaths, they have no portion in the Hereafter) (Aal `Imran 3:77).
In addition, Abu Dhar (may Allah be pleased with him) narrated that the Prophet (peace and blessings be upon him) said, “Three are the (persons) with whom Allah would not speak on the Day of Resurrection, or look at, or absolve, and for whom there will be a painful chastisement.” The Messenger of Allah (peace and blessings be upon him) repeated this thrice. Abu Dhar remarked, “They have failed and lost; who are these persons, Messenger of Allah?” He (peace and blessings be upon him) replied, “They are the one who drags his garment (in haughtiness), the almsgiver who reminds others of his favors, and the seller of goods by false oath” (Reported by Muslim).
Furthermore, Salman (may Allah be pleased with him) narrated that the Messenger of Allah (peace and blessings be upon him) said, “Three are the persons at whom Allah will not look on the Day of Judgment: the old man who commits fornication, the haughty person who is (poor and) a provider for dependents, and a man f
or whom Allah has provided goods which he neither sells nor buys except with an oath.” (Reported by At-Tabarani in his three lexicons. Sheikh Al-Albani regarded the hadith as authentic in his Sahih Al-Jami` As-Saghir vol. 1, p. 589.) In another narration of the same hadith, the last statement is“A man who regards oaths as goods; he takes an oath in everything no matter true or false.” (Reported by At-Tabarani. Sheikh Al-Albani regarded it as good.) Thus, merchants have to fear Allah and not take many oaths.
In this regard, Abu Hamid Al-Ghazali states, “A merchant should not swear at all, for if he is lying, he will be committing perjury, which turns homes into wastelands. If he is truthful, he will be using Allah’s name in his oaths, but the worldly life is cheaper than being promoted through mentioning Allah’s name unnecessarily. Thus, due to the fact that praising a commodity truthfully is dispraised as it will not augment provision, taking false oaths entails severe punishment” (Ihya’ `Ulum Ad-Din, vol. 2, p.77).
Lastly, if a merchant swears much, he has to give much charity, as the Prophet (peace and blessings be upon him) says, “O merchants, selling involves much vain talk and swearing, so mix it with charity.” (Reported by Abu Dawud, At-Tirmidhi, An-Nasa’i, Ibn Majah. It is an authentic hadith as regarded by Sheikh Al-Albani in Sahih Sunan Abu Dawud vol. 2, p. 640.)