Short answer
Yes, breaking a promise without a valid excuse is a sin, and the Prophet ﷺ named it a sign of hypocrisy. If you meant to keep it and something truly stopped you, there is no sin. Making a promise you never intend to keep is lying. A promise is not a vow: a vow is made to Allah and has its own rules.
Keeping a promise is strongly required, and breaking it without excuse is sinful. Promising while intending not to fulfil it is a lie. A promise is not an oath, so breaking it has no kaffarah unless you swore by Allah. In general a simple promise is binding before Allah but not enforced in court.
Other madhhabs
- Maliki
- A promise that led the other person to take on a cost is enforceable in court.
Explanation
The Quran says: fulfil every commitment, for commitments will be asked about. It also asks the believers why they say what they do not do. The Prophet ﷺ said that the signs of a hypocrite are three: when he speaks he lies, when he promises he breaks it, and when he is trusted he betrays.
The scholars explain three situations:
- You promise and mean it, then cannot: illness, an emergency or something outside your control. No sin. Let the person know as early as you can.
- You promise and mean it, then simply change your mind: blameworthy and sinful if there is no good reason, since you broke your word.
- You promise while planning not to keep it: this is lying, and it is the hypocrite's trait in the hadith.
Saying 'in sha Allah' with a promise is the sunnah, but it is not a way out. Saying it while planning to break your word is still deceit.
A promise, an oath and a vow are different. A promise is your word to a person. An oath is swearing by Allah; breaking one needs kaffarah (see kaffarah for breaking an oath). A vow (nadhr) is making an act of worship binding on yourself; see fulfilling a vow. Promises to children count too: telling a child 'I'll buy you a toy' and not meaning it teaches them that lying is normal.
The evidence
Quran, Surah Al-Israa 17:34
وَلَا تَقْرَبُوا۟ مَالَ ٱلْيَتِيمِ إِلَّا بِٱلَّتِى هِىَ أَحْسَنُ حَتَّىٰ يَبْلُغَ أَشُدَّهُۥ ۚ وَأَوْفُوا۟ بِٱلْعَهْدِ ۖ إِنَّ ٱلْعَهْدَ كَانَ مَسْـُٔولًۭا ﴿٣٤﴾
And do not approach the property of an orphan, except in the way that is best, until he reaches maturity. And fulfill [every] commitment. Indeed, the commitment is ever [that about which one will be] questioned.
Every commitment will be asked about on the Day of Judgement.
Quran, Surah As-Saff 61:2
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لِمَ تَقُولُونَ مَا لَا تَفْعَلُونَ ﴿٢﴾
O you who have believed, why do you say what you do not do?
Saying one thing and doing another is blamed.
Sahih al-Bukhari 33
Sahih... آية المنافق ثلاث إذا حدث كذب وإذا وعد أخلف ...
"The signs of a hypocrite are three: when he speaks he lies, and when he promises he breaks it, and when he is trusted he betrays."
Breaking promises is a trait of hypocrisy.
Where the ruling is recorded
- Radd al-Muhtar (Ibn Abidin), Kitab al-Buyu', on promises (wa'd). A promise is binding before Allah though not generally enforced by a judge.
- Fiqh al-Buyu' (Mufti Taqi Usmani), Section on binding promises. Discusses when a promise becomes enforceable, including the Maliki view.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. 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.