1 One should only swear in name of Allah:
One should only swear in the name of Allah and should never swear in name of any human being. Here are some hadiths which clarify this point:
Narrated Ibn 'Umar radi Allahu anhu:Allah's Apostle met 'Umar bin Al-Khattab while the latter was going with a group of camel-riders, and he was swearing by his father. The Prophet said, "Lo! Allah forbids you to swear by your fathers, so whoever has to take an oath, he should swear by Allah or keep quiet." (Sahih Bukharee,Volume 8, Book 78, Number 641)
Narrated 'Abdullah bin 'Umar radi Allahu anhur:Allah's Apostle said, "Do not swear by your fathers." (Sahih Bukharee,Volume 8, Book 78, Number 643)
Narrated Abu Huraira radi Allahu anhu :The Prophet said, "Whoever swears saying in his oath. 'By Al-Lat and Al'Uzza,' should say, 'None has the right to be worshipped but Allah; and whoever says to his friend, 'Come, let me gamble with you,' should give something in charity."( Sahih Bukharee,Volume 8, Book 78, Number 645)
2 One should fulfil and take care of his oath:
A person should be careful about his oath and should try his best to fulfil his oath.Some of the hadiths highlighting this point are as follows:
Narrated Al-Bara: The Prophet ordered us to help others to fulfill the oaths. (Sahih Bukharee,Volume 8, Book 78, Number 648)
Narrated 'Abdullah:The Prophet was asked, "Who are the best people?" He replied: The people of my generation, and then those who will follow (come after) them, and then those who will come after the later; after that there will come some people whose witness will precede their oaths and their oaths will go ahead of their witness." Ibrahim (a sub-narrator) said, "When we were young, our elder friends used to prohibit us from taking oaths by saying, 'I bear witness swearing by Allah, or by Allah's Covenant."' (Sahih BukhareeVolume 8, Book 78, Number 652)
3 Allah will forgive forgetfulness in oaths/ unintentional oaths:
It is the mercy of Allah swt that He will not punish those people who unintentionally swore in His name without attentive heart.Some of the verses of Quran related to issue are as follows:
Allâh will not call you to account for that which is unintentional in your oaths, but He will call you to account for that which your hearts have earned. And Allâh is Oft-Forgiving, Most-Forbearing. (Al-Baqarah 2:225)
And there is no sin on you if you make a mistake therein, except in regard to what your hearts deliberately intend. And Allâh is Ever OftForgiving, Most Merciful. (Al-Ahzab 33:5)
Allâh will not punish you for what is uninentional in your oaths, but He will punish you for your deliberate oaths(Al-Ma'idah 5:89)
4 There is severe punishment for false oath:
Any one who takes a false oath with bad intention he will have to face severe torment on the day of Judgement.The hadiths which clarifies this point is as follows:
Narrated 'Abdullah:The Prophet said, "Whoever swears falsely in order to grab the property of a Muslim (or of his brother), Allah will be angry with him when he meets Him." Allah then revealed in confirmation of the above statement:--'Verily those who purchase a small gain at the cost of Allah's Covenant and their own oaths.' (3.77) Al-Ash'ath said, "This Verse was revealed regarding me and a companion of mine when we had a dispute about a well." (Sahih Bukharee,Volume 8, Book 78, Number 653)
5 One should break oath of sin
When someone takes oath of sin he must break this oath because if he will try to mantain his oath he will earn more sins.Hadith related to this issue is as follows:
Narrated Abu Huraira:Allah's Apostle said, "Anyone who takes an oath through which his family may be harmed, and insists on keeping it, he surely commits a sin greater (than that of dissolving his oath). He should rather compensate for that oath by making expiation." (Sahih Bukharee,Volume 8, Book 78, Number 622)
Narrated Abu Huraira:The Prophet said, "We (Muslims) are the last in the world, but will be foremost on the Day of Resurrection." Allah's Apostle also said, "By Allah, if anyone of you insists on fulfilling an oath by which he may harm his family, he commits a greater sin in Allah's sight than that of dissolving his oath and making expiation for it." (Sahih Bukharee,Volume 8, Book 78, Number 621)
6 When some one breaks an oath he should compensate by making expiation:
In case of need ,emergency and to benefit humanity one can breaks his oath and can compensate it by making expiation .A verse of Quran and some hadiths related to issue are as follows:
Allâh will not punish you for what is uninentional in your oaths, but He will punish you for your deliberate oaths; for its expiation (a deliberate oath) feed ten Masâkin (poor persons), on a scale of the average of that with which you feed your own families; or clothe them; or manumit a slave. But whosoever cannot afford (that), then he should fast for three days. That is the expiation for the oaths when you have sworn. And protect your oaths (i.e. do not swear much). Thus Allâh make clear to you His Ayât (proofs, evidences, verses, lessons, signs, revelations, etc.) that you may be grateful. (Al-Ma'idah 5:89)
Narrated 'Abdur-Rahman bin Samura:The Prophet said, "O 'Abdur-Rahman bin Samura! Do not seek to be a ruler, because if you are given authority for it, then you will be held responsible for it, but if you are given it without asking for it, then you will be helped in it (by Allah): and whenever you take an oath to do something and later you find that something else is better than the first, then do the better one and make expiation for your oath." (Sahih Bukharee,Volume 8, Book 78, Number 619)
Narrated 'Aisha:Abu Bakr As-Siddiq had never broken his oaths till Allah revealed the expiation for the oaths. Then he said, "If I take an oath to do something and later on I find something else better than the first one, then I do what is better and make expiation for my oath."(Sahih Bukharee,Volume 8, Book 78, Number 618)
Conclusion:
1 One should not play with oaths
2 One can take oath in case of Need
3 One should not swear in name of any one other than Allah swt
4 One should fulfil his oath
5 The person who takes false oath will be severly punished by Allah swt
6 One should not fulfil oath of sin
7 If some one breaks his oath he should make expiation for it
8 the expiation of oath according to Quran is
a ) Feeding ten Masâkin (poor persons), on a scale of the average of that with which you feed your own families
or
b) Clothing ten Masakins (poor persons)
or
c) Setting a slave free
or
d) One who cannot afford (that), then he should fast for three days.