Swearing for the sake of emphasis

Not only it is permitted but it is mustahab to swear in order to emphasize on a true fact, or to prove some fact, or to show its importance. For example the Holy Prophet (s.a.w.s.) speaks after taking the oath: 
"By Allah! Allah does not delay in forgiving, Though you may be lazy in seeking it." 
(Masaalik)

Another example of an oath is the following saying of Amirul Momineen (a.s.): 
"By Allah! If people knew what I know then very few would have laughed and many more would have wept." 
(Masaalik)

There are numerous Quranic verses and the traditions of Masoomeen (a.s.) where oath is taken. All of them are of this same type. They are for emphasis and for proving particular facts.

A person wrote a letter to Imam Muhammad Baqir (a.s.) and asked about something which was being wrongly attributed to him (Imam a.s).

Imam Baqir (a.s.) wrote the following reply, 
"By Allah! What is being attributed is not correct. But under no circumstance do I like to say "By Allah" to disprove it. Yet I regret that such a thing is being said when it really isn't so." 
(Mustadrakul Wasael)

Swearing is Makrooh

We have already described the wajib and Mustahab oaths. Apart from these, in all other situations, it is Makrooh (detestable) to swear. It is irrelevant whether the oath is for something past, present or future. In ordinary situations, for ordinary matters, taking an oath is Makrooh. Swearing for a false thing is certainly Haraam. It is the command of Imam Ja'far as-Sadiq (a.s.):
"Do not swear by the name of Allah, whether you are speaking the truth or lying." 
(Furu Al Kafi)

"Because Allah says in the Holy Quran,
"And make not Allah because of your swearing (by Him) an obstacle to your doing good...""
(Surah Baqarah 2:224)

Hazrat Imam Ja'far as-Sadiq (a.s.) also says, 
"One who swears falsely by Allah for a lie has disbelieved, and one who swear by Allah for truth has sinned, because Allah says: "Do not use Allah for (taking of) your oaths." 
(Furu Al Kafi)

The above quoted traditions could be simply explained thus: 
To swear falsely in the name of Allah is definitely a greater sin and one who indulges in a greater sin, falls down from the highest position of Faith. Due to this some amount of disbelief comes to his heart. Imam (a.s.) has also called a true oath a sin and he has used the word "Ithm" (sin). Since it is prominent among the Mujtahids that a true oath is Makrooh the word "Ithm" would imply something which is very very undesirable.

A Lesson from Hazrat Isa (a.s.)

The book Furu Al Kafi also contains the following report from Imam Ja'far as-Sadiq (a.s.):
"The apostles of Hazrat Isa (a.s.) came to him and said, "O the teacher of good, give us some advice."

He (a.s.) said, "Certainly, Musa, the Prophet of Allah commanded you not to swear falsely by Allah. And I order you not to swear falsely and (nor) truly." 
(Furu Al Kafi)

Oath of respectable objects and personalities

Wherever it is permitted to swear by Allah, it is also permitted to swear by other honorable personalities or respectable objects. In such situations it is allowed to take an oath by the Quran, the Ka'ba, the Prophet (s.a.w.s.) or the Imam (a.s.). In the same way oath upon any other respectable object is also permissible. For example a person may swear by his father or son etc.

Those traditions that prohibit swearing by Allah's name prohibit it for proving ones right. They do not prohibit the proving of a true fact by oath. However when a situation arises where it becomes obligatory to take an oath, then one must swear only by Allah. Oath by any other object or personality will not be absolutely correct and from the Shariat point of view the matter will not end conclusively. Similarly if one has to take an oath for performing a particular action in the future, in this case too, one must swear only by Allah. Any other vow does not have any legal standing.

The oath that is haraam under all circumstances

The oath which is Haraam under all circmstances and which one can never take is that of dissociating with Allah and His religion. For example a man says;
"If I do not perform this particular action, I shall be dissociated with Allah and His religion." Such an oath is certainly Haraam.

In the same way if one says: 
"If I do not do this, I would have disbelieved in the Holy Prophet (s.a.w.s.), or I would have rejected the Mastership of Ali (a.s.), or I would become a disbeliever." Such a vow is also Haraam. It is Haraam whether one wishes to prove the truth or to lay emphasis upon a fact.

The Holy Prophet (s.a.w.s.) heard a person taking such an oath. He (s.a.w.s.) said, "Woe be unto you, if you leave the religion of Muhammad (s.a.w.s.) then which religion would you follow?"

The narrator says that the Holy Prophet (s.a.w.s.) did not speak to this man till the end of his life. 
(Al Kafi)

Imam Ja'far as-Sadiq (a.s.) informed Yunus Ibne Zabyan: 
"O Yunus! Do not speak about dissociating from us in an oath. One who takes oath from it, whether for a true thing or a falsehood, he really becomes dissociated from us." 
(Al Kafi)

Expiation for a haraam oath

The expiation for an oath which is haraam, (the oath which states dissociation with divine personalities), according to a group of Mujtahids is equal to expiation of Zihar (when one vows to abstain from one's wife, sexually). Another group of Mujtahids has prescribed its expiation to be equal to that of breaking a vow and it is the same as the penalty of breaking or not keeping a Wajib fast of Ramazan. 
(Refer Shariyatul Islam)

However, Shaykh Mufeed (r.a.) says that expiation of vow of dissociation is to feed to satiation, ten poor people and also to repent. The same decree is proved from a letter of Imam Hasan al-Askari (a.s.), which is quoted in the book Masaalik.

Imam (a.s.) says, 
"He shall feed ten poor people with a 'Madd' (approximately ¾ of a kilo) of food and seek forgiveness from Allah."

In this penalty, the following edibles can be given: wheat, wheat flour, barley, rice or any other cooked food.

Since the chain of narrators for this tradition is authentic, one must act upon it as a precautionary measure.

Imam Ja'far as-Sadiq (a.s.) and Mansur Dawaniqi

A man came to the Abbaside king Mansur Dawaniqi and began to instigate him against Imam Ja'far as-Sadiq (a.s.). He said, "He desires to launch an attack upon you. He has sent money to different places for this and continues to do so. He has always supported the sons of Abdullah Ibne Hasan, Muhammad and Ibrahim, and these two have confronted you."

Mansur summoned Imam Ja'far as-Sadiq (a.s.) from Madinah. When Imam (a.s.) reached the court of Mansur, he quoted the false allegations and severely criticised the Imam (a.s.).

Imam (a.s.) replied, 
"I seek the refuge of Allah from such things. All these are false allegations."

Mansur called the man who had laid these false allegations against Imam (a.s.). The accused man came and repeated his accusations. Imam as-Sadiq (a.s.) asked him, 
"Can you swear for the truth of your statements?"

This accused person began to say, "By Allah! The one besides whom there is no god, He is the..."

Imam (a.s.) interrupted him, 
"Do not make haste in taking the oath, say as I command you."

Mansur asked, "Is there any defect in the oath which he has taken?"

Imam replied, 
"When a man swears by Allah, praising the Divine qualities, Allah refrains from sending an immediate retribution. So he should say like this, 'I swear by Allah ignoring His Might and Power and seek the refuge on my own might and power that whatever I have said is the truth.'"

Mansur ordered that man to swear in this manner. The man began to take the oath and had not even completed it when his tongue rolled out like a dog and he fell down dead.

Is it against a prohibited oath?

Someone may think that this narration mentions the prohibited form of oath. It is not so. Muhaqqiqe-Qummi says that in the first place the chain of narrators of this tradition is weak. Secondly it may be that ordering such an oath may be the sole prerogative of an Imam. The Imam (a.s.) knew that the one taking such an oath is not a believer. He was an enemy of Ahlul Bayt (a.s.) and it was necessary to resort to such means in order to clear himself of the false allegations. 
(Jame ush-shataat)

From the explanation of this tradition by Muhaqqiq it is clear that Imam (a.s.) considered that accursed man deserving of death and his death only depended upon the oath of dissociation. It was also necessary that Imam (a.s.) was not disrespected and that the Imam (a.s.) could save himself from being unjustly persecuted at the hands of Mansur. Another benefit that accrued was that, Mansur for the time being, refrained from oppressing the other Sadaat (descendants of Holy Prophet) and believers.

Repenting for a false oath

The method of repenting for a false oath is that one must feel extremely remorseful for it. He should know that he has considered the Divine name of Allah to be a plaything, and that he has committed a grave sin. The more remorse one feels and the more serious he considers his sin, the closer he shall be to Allah's Divine Mercy and Forgiveness. If due to this false oath some monetary loss has occurred to a believer or a believer has been insulted, then the one who had taken the false oath must compensate for the monetary loss and apologise to the believer, and as far as possible try to make up for the harm that has been caused due to his false swearing.

When is the vow correct?

There are some requirements for the correctness of a vow that a person takes for performing or avoiding particular actions in the future. If all the requirements are fulfilled then it is haraam to break this vow. If it is broken, expiation becomes wajib.

The following are the conditions for such vows:
1. The vow should be with regard to a wajib or a Mustahab act. For example, he can vow that he shall not intentionally avoid the Morning Prayer, he will make it a point to say Namaz-e-Shab. In the same way if one vows to abstain from a particular act, this act has to be either haraam or Makrooh in nature. For example he can vow that he shall not speak a lie in future or he can vow to refrain from spitting in the mosque. A vow to refrain from a Mubah (permitted) act or thing should only be taken when there is some benefit in it. For example it is Mubah to smoke. So one can take a vow in order to give up this habit.

2. Vows with regard to all the five types of actions, i.e. Wajib, Mustahab, Haraam, Makrooh and Mubah are valid only when the name of Allah is uttered with a firm intention to do or to refrain from a particular thing. One must not swear by Allah in jest. If one is in a habit of saying, "By Allah I shall do this." or "By Allah I shall not do it" then unless he seriously means it, such a vow is not considered valid.

The Quran says: 
"Allah does not call you to account for what is vain in your oaths, but he calls you to account for the making of deliberate oaths; so its expiation is feeding of ten poor men out of the middling (food) you feed your families with, or their clothing, or the freeing of a neck; but whosoever cannot find (means) then fasting for three days; this is the expiation of your oaths when you swear; and guard your oaths. Thus does Allah make clear to you His communications, that you may be grateful.
(Surah Maidah 5:89)

Useless Vow

From the foregoing discussion we can conclude that a vow is only valid when there is some inherrent good or evil in the concerned action. Therefore one can take a vow only for acts that one is inclined towards or those that are wajib or mustahab. Similarly if a person vows to refrain from a particular action he must feel an aversion to it or it should be something makrooh or haraam. Hence to vow to perform some lewd action is itself lewdness. Such a vow is invalid from Shariat point of view. We must never vow to perform evil acts whether it is evil according to reason or according to Shariat.

It is haraam for one to vow to omit wajib or mustahab prayers or vow not to speak to ones mother or any other relative. It is also not allowed to vow against performing Hajj if one is capable of doing so. To vow that one would never mediate between two believers is also haraam. All such vows are invalid. Hence if one has ever taken such vows one must repent for them.

Hazrat Imam Ja'far as-Sadiq (a.s.) says,
"If one takes a vow to refrain from a beneficial act he must perform it (and disregard the vow). There is no kaffarah for breaking such a vow. It is only a satanic instigation."
(Al Kafi)

Although apparently the above tradition and other such reports imply that a vow for a mubah act which is beneficial is invalid, the mujtahids are of the opinion that one must exercise caution and in case such a vow is broken, kaffarah should be paid. According to the majority of the jurists a mubah thing becomes wajib if one takes a vow for it. Thus the best thing is to follow the path of precaution.

Saeed Aeraaj, a narrator of traditions says that he asked Imam Ja'far as-Sadiq (a.s.) about a person who had vowed to do a particular thing, whereas the avoidance of that was more beneficial, and now the person himself was worried to disregard his vow. Imam (a.s.) said,
"Have you not heard the Messenger of Allah (s.a.w.s.) say that whenever you find that you have vowed against doing something that is better to be done, you must ignore your vow?"
(Al-Kafi)

Types of Vows

In the same book, Al Kafi we have a tradition of Imam as-Sadiq (a.s.) that he said,
There are three types of Vows:
1. A vow that makes hell incumbent.
2. A vow that makes kaffarah wajib.
3. A vow that neither earns hell nor entails kaffarah.

A vow that makes hell incumbent is a false one. It is a vow that proves harmful to the Muslims. It is called 'Yaman Ghamoos' in the religious terminology.

A vow that entails Kaffarah is one that is taken to perform a charitable act or taken to refrain from an evil act. If a person breaks such a vow he is liable to pay kaffarah for the same. In addition he must feel remorse for it and repent.

Lastly, a vow that neither earns hell nor makes kaffarah wajib is the vow of doing Qat-e-Rehmi taken under duress before a tyrant ruler, parents or ones spouse. Other vows like the doing of some evil act or to refrain from a wajib are also included in this category. Those who wish to study in detail may refer to the comprehensive books of jurisprudence.