Surah Al-Maaida (5) — Ayah 89

89. Allah will not call you to account for your idle oaths, but He will hold you accountable for the oaths you swear in earnest [132]. So its expiation [132.1] is to feed ten needy people with the average of what you feed your own families, or to clothe them, or to free a slave. But whoever cannot afford that, then he must fast for three days. That is the expiation for your oaths when you have sworn and broken them. And guard your oaths. Thus Allah makes clear to you His commandments so that you may be grateful.

[132] Please consider the following hadiths related to the issues of oaths:
1. Sayyidah Aisha (may Allah be pleased with her) says that by "vain oaths" are meant those oaths which a person utters habitually (without intention), such as: «لا والله» «بلي والله» She also says that her father (Sayyiduna Abu Bakr Siddiq ؓ) never broke an oath until Allah revealed the verse of expiation. At that time, he began to say: "When I take an oath and then consider something else better, I accept Allah's concession and do what I consider better." [بخاري كتاب التفسير]
2. Sayyiduna Umar says that the Prophet said: "If anyone has to swear an oath, let him swear by Allah, otherwise remain silent." [بخاري كتاب الايمان والنذور۔ مسلم۔ كتاب الايمان۔ باب النهي عن الحلف بغير الله تعالىٰ ]
3. The Prophet said: "Whoever swears by anything other than Allah has committed shirk." [ابو داؤد۔ كتاب الايمان والنذور باب۔ فى كراهية الحلف بالابائ]
4. The Prophet said: "Do not swear by your fathers, nor by your mothers, nor by your partners, and swear by Allah only when you are truthful." [ابو داؤد۔ كتاب الايمان والنذور باب۔ فى كراهيه الحلف بالاباء نسائي۔ كتاب الايمان والنذور۔ باب الحلف بالامهات]
5. The Prophet said: "The major sins are these: associating partners with Allah, harming parents, killing someone, and taking a false oath." [بخاري۔ كتاب الايمان والنذور۔ باب اليمين الغموس __QUR_0__ النحل :94]
6. The Prophet said: "Whoever swears to do something and then says 'InshaAllah,' there will be no sin upon him (for breaking the oath)." [ترمذي۔ ابو اب النذور والايمان۔ باب فى الاستثناء فى اليمين]
7. Sayyiduna Bara bin Azib says: "The Prophet commanded the fulfillment of the oath of the one who administers the oath." [بخاري۔ كتاب الايمان والنذور باب واقسموا بالله جهد ايمانهم]
8. The Prophet said: "In an oath, the intention of the one who makes another swear will be considered." [مسلم۔ كتاب الايمان والنذور۔ باب اليمين على نية المستحلف]
9. The Prophet said: "If you swear to do something, and then you see something else as better, then pay the expiation for your oath and do what is better." [بخاري۔ كتاب الايمان والنذور۔ باب : __QUR_1__ [البقرة :225] Muslim. Book of Faith. Chapter: Recommendation for one who swears an oath [N]
[132۔1]

Types of Oaths:

From Arabic speech, it is known that among the Arabs, it was common to swear oaths on every little thing. Most of these oaths were either uttered habitually or to add eloquence to speech. For such oaths, Allah Almighty has used the word "vain," for which there is no expiation. As for those oaths that are taken with the intention of the heart, they are also of two types: one is that which is taken on something correct, and if it relates to the future, it should be fulfilled accordingly. For such oaths, the question of expiation does not arise. The second type is the oath that relates to the future, and the act upon which the oath is taken is not forbidden, but it would have been better not to swear on it. For example, once the Messenger of Allah himself swore not to drink honey in the future, so Allah Almighty admonished him for this [التحريم آيت : 1]
Or a companion saw a chicken pecking at filth and swore not to eat chicken in the future. Such oaths should also be broken and their expiation paid, as is clear from hadith number 1 and hadith number 9 mentioned above.

Oaths and Their Expiation — The Common Factor of Freeing a Slave in Expiation:

The literal meaning of "kaffarah" (expiation) is to perform a good deed that covers or erases a previously committed bad deed. In the Noble Quran and hadiths, many sins are mentioned for which expiations are prescribed. For example, the expiation for accidental killing, the expiation for zihar, the expiation for hunting while in the state of ihram, the expiation for breaking an obligatory fast, the expiation for breaking an oath, and the expiation for injuring someone, etc. In most of these expiations, the common factor is the freeing of a slave. As is the case in the expiation for breaking an oath, from which it is understood that, from the Islamic point of view, the practice of slavery was a condemned thing that was gradually abolished. Today, praise be to Allah, the practice of slavery no longer exists. Therefore, the remaining three alternative forms of expiation for an oath are: feeding ten needy people with average food according to one's means, or providing clothing to ten needy people, or fasting for three days. Now, it is not necessary to gather ten needy people and feed them together; rather, the equivalent amount can be given to ten needy people, or to one, or to two or three needy people. The same applies to providing clothing. And regarding fasting, apparently, there is no restriction in this verse that the three days must be consecutive. There is flexibility that these fasts can be observed on separate days as well.