Short answer
Swearing by anything other than Allah, such as your mother's life, your children or the Kaaba, is not allowed: the Hanafi school rates it makruh tahrimi, and it is not a valid oath. Swearing by the Quran is a valid oath in the later Hanafi fatwa, because the Quran is Allah's speech.
Swearing by other than Allah, His names or His attributes is makruh tahrimi and is not a binding oath, so breaking it has no kaffarah. It becomes shirk if one reveres the thing as Allah is revered. Swearing by the Quran is a valid oath in the relied-upon later fatwa.
Other madhhabs
- Shafi'i
- Swearing by other than Allah is makruh (disliked), and disbelief if one reveres the thing as Allah is revered.
- Hanbali
- Swearing by other than Allah is haram. One narration from Imam Ahmad made an oath by the Prophet ﷺ binding.
Explanation
An oath is a solemn act that calls on Allah as witness, so it belongs to Him alone. The Prophet ﷺ heard Umar swear by his father and said that Allah forbids you to swear by your fathers: whoever swears should swear by Allah or stay silent. In another hadith he called swearing by other than Allah a form of kufr or shirk. The scholars explain this as minor shirk in most cases, and major shirk when a person gives the thing the reverence due to Allah.
Common phrases and their status:
- 'I swear on my mother's life', 'on my kids', 'on my life', 'I swear on the Kaaba': not allowed and not a valid oath.
- 'Wallahi', 'By Allah', 'I swear to God': valid oaths. Use them only when you mean them.
- 'I swear on the Quran': a valid oath in the later Hanafi fatwa, because the Quran is Allah's speech and people treat it as an oath by Allah.
If the phrase slips out by habit, the Prophet ﷺ taught that whoever swears by an idol should say La ilaha illallah. Scholars apply this to any oath by other than Allah: say it, ask forgiveness and train your tongue.
Even true oaths by Allah should not be thrown around. Allah does not hold you to careless oaths said without intention, but a deliberate oath you break needs kaffarah. You can work it out with the kaffarah calculator.
The evidence
Quran, Surah Al-Maaida 5:89
لَا يُؤَاخِذُكُمُ ٱللَّهُ بِٱللَّغْوِ فِىٓ أَيْمَٰنِكُمْ وَلَٰكِن يُؤَاخِذُكُم بِمَا عَقَّدتُّمُ ٱلْأَيْمَٰنَ ۖ فَكَفَّٰرَتُهُۥٓ إِطْعَامُ عَشَرَةِ مَسَٰكِينَ مِنْ أَوْسَطِ مَا تُطْعِمُونَ أَهْلِيكُمْ أَوْ كِسْوَتُهُمْ أَوْ تَحْرِيرُ رَقَبَةٍۢ ۖ فَمَن لَّمْ يَجِدْ فَصِيَامُ ثَلَٰثَةِ أَيَّامٍۢ ۚ ذَٰلِكَ كَفَّٰرَةُ أَيْمَٰنِكُمْ إِذَا حَلَفْتُمْ ۚ وَٱحْفَظُوٓا۟ أَيْمَٰنَكُمْ ۚ كَذَٰلِكَ يُبَيِّنُ ٱللَّهُ لَكُمْ ءَايَٰتِهِۦ لَعَلَّكُمْ تَشْكُرُونَ ﴿٨٩﴾
Allah will not impose blame upon you for what is meaningless in your oaths, but He will impose blame upon you for [breaking] what you intended of oaths. So its expiation is the feeding of ten needy people from the average of that which you feed your [own] families or clothing them or the freeing of a slave. But whoever cannot find [or afford it] - then a fast of three days [is required]. That is the expiation for oaths when you have sworn. But guard your oaths. Thus does Allah make clear to you His verses that you may be grateful.
Oaths are serious, and a broken deliberate oath requires expiation.
Sahih al-Bukhari 6646
Sahih... إن الله ينهاكم أن تحلفوا بآبائكم من كان حالفا فليحلف بالله أو ليصمت ...
"Allah forbids you to swear by your fathers. Whoever swears, let him swear by Allah or keep silent."
Oaths may only be by Allah.
Jami' at-Tirmidhi 1535
Graded sahih... من حلف بغير الله فقد كفر أو أشرك ...
"Whoever swears by other than Allah has committed kufr or shirk."
Swearing by other than Allah is a grave sin.
Sahih al-Bukhari 4860
Sahih... من حلف فقال في حلفه واللات والعزى فليقل لا إله إلا الله ...
"Whoever swears and says in his oath 'by al-Lat and al-Uzza', let him say La ilaha illallah."
The remedy for a wrong oath is to renew tawhid.
Where the ruling is recorded
- al-Hidaya, Kitab al-Ayman, chapter on what counts as an oath. An oath by other than Allah is not a valid oath.
- al-Durr al-Mukhtar, Kitab al-Ayman. Swearing by the Quran is counted as a valid oath in the later fatwa.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.