We mentioned the subject of unintentional oaths in Surat Al-Baqarah, all praise and thanks are due to Allah, and so we do not need to repeat it here. We also mentioned that the Laghw in oaths refers to one's saying, "No by Allah," or, "Yes, by Allah," unintentionally.
Allah said,
وَلَـكِن يُؤَاخِذُكُم بِمَا عَقَّدتُّمُ الاٌّيْمَـنَ
(but He will punish you for your deliberate oaths.) in reference to the oaths that you intend in your hearts,
فَكَفَّارَتُهُ إِطْعَامُ عَشَرَةِ مَسَـكِينَ
(for its expiation (a deliberate oath) feed ten poor,), who are needy, not able to find necessities of the life. Allah's statement,
مِنْ أَوْسَطِ مَا تُطْعِمُونَ أَهْلِيكُمْ
(on a scale of the Awsat of that with which you feed your own families;) means, "On the average scale of what you feed your families," according to Ibn `Abbas, Sa`id bin Jubayr and `Ikrimah. `Ata' Al-Khurasani commented on the Ayah, "From the best of what you feed your families". Allah's statement,
أَوْ كِسْوَتُهُمْ
(or clothe them,) refers to clothing each of the ten persons with what is suitable to pray in, whether the poor person was male or female. Allah knows best. Al-`Awfi said that Ibn `Abbas said that the Ayah means a robe or garment for each poor person (of the ten). Mujahid also said that the least of clothing, referred to in the Ayah, is a garment, and the most is whatever you wish. Al-Hasan, Abu Ja`far Al-Baqir, `Ata', Tawus, Ibrahim An-Nakha`i, Hammad bin Abi Sulayman and Abu Malik said that it means (giving each of the ten poor persons) a garment each. Allah's statement,
أَوْ تَحْرِيرُ رَقَبَةٍ
(or free a slave) refers to freeing a believing slave. In the Muwatta' of Malik, the Musnad of Ash-Shafi`i and the Sahih of Muslim, a lengthy Hadith was recorded that `Umar bin Al-Hakam As-Sulami said that he once had to free a slave (as atonement) and he brought a black slave girl before the Messenger of Allah ﷺ , who asked her;
«أَيْنَ اللهُ؟»
(Where is Allah) She said, "Above the heavens." He said,
«مَنْ أَنَا؟»
(Who am I) She said, "The Messenger of Allah." He said,
«أَعْتِقْهَا فَإِنَّهَا مُؤْمِنَة»
(Free her, for she is a believer.) There are three types of expiation for breaking deliberate oaths, and whichever one chooses, it will suffice, according to the consensus (of the scholars). Allah mentioned the easiest, then the more difficult options, since feeding is easier than giving away clothes, and giving away clothes is easier than freeing a slave. If one is unable to fulfill any of these options, then he fasts for three days for expiation, just as Allah said,
فَمَن لَّمْ يَجِدْ فَصِيَامُ ثَلَـثَةِ أَيَّامٍ
(But whosoever cannot afford (that), then he should fast for three days.) Ubayy bin Ka`b and Ibn Mas`ud and his students read this Ayah as follows, "Then he should fast three consecutive days." Even if this statement was not narrated to us as a part of the Qur'an through Mutawatir narration, it would still be an explanation of the Qur'an by the Companions that has the ruling of being related from the Prophet . Allah's statement,
ذلِكَ كَفَّارَةُ أَيْمَـنِكُمْ إِذَا حَلَفْتُمْ
(That is the expiation for the oaths when you have sworn.)5:89 means, this is the legal way to atone for deliberate oaths,
وَاحْفَظُواْ أَيْمَـنَكُمْ
(And protect your oaths.) Do not leave your broken oaths without paying the expiation for them, according to the meaning given by Ibn Jarir.
كَذَلِكَ يُبَيِّنُ اللَّهُ لَكُمْ آيَـتِهِ
(Thus Allah makes clear to you His Ayat) and explains them to you,
لَعَلَّكُمْ تَشْكُرُونَ
(that you may be grateful.)