Nadhr
Nadhr is a vow - binding yourself to do something for Allah that was not already required. The Prophet ﷺ discouraged making vows, but once one is made it must be kept. A vow to give charity is a debt owed, not a donation.
Charity given freely, with no vow attached, is Sadaqah.
What the Word Means
A nadhr is a pledge: a person obliging themselves to do something Allah had not obliged them to do.
In South Asia and across British Muslim households the same idea is usually called mannat, and in parts of the Arab world you will hear nadhr used for the thing given as much as for the promise.
Typically it takes a conditional form. If my mother recovers, I will fast ten days. If I get this job, I will feed a hundred people. Something wanted, and something offered in return.
The Qur'an Praises Those Who Keep Them
The righteous are described in the Qur'an as people who fulfil their vows and fear a day whose evil is widespread (Qur'an 76:7). Elsewhere pilgrims are instructed to complete their rites and fulfil their vows (Qur'an 22:29).
The clearest examples come from one family. The mother of Maryam pledged what was in her womb to the service of her Lord before the child was born (Qur'an 3:35). And Maryam herself, instructed what to say when she returned carrying her son, says: I have vowed a fast to the Most Merciful, so I will not speak to anyone today (Qur'an 19:26).
Keeping a vow, then, is plainly a virtue.
And the Prophet ﷺ Told People Not to Make Them
Which makes the next part startling.
Ibn Umar reported that the Prophet ﷺ forbade vowing, and said that it does not prevent anything - it only makes a miser spend his property (Sahih al-Bukhari 6608).
Imam Muslim files his whole chapter under a heading saying as much: the prohibition of vows, and confirmation that they avert nothing. Imam al-Bukhari files his under the Book of Divine Decree, which tells you what he thought the issue was.
And there is a hadith qudsi that makes the reasoning explicit. Allah says that the vow brings the son of Adam nothing that has not already been decreed for him - but the vow may coincide with what was decreed, and by this a miser is made to spend. He gives what he would never have given, were it not for his vow (Sahih al-Bukhari 6694).
Read that carefully. The vow does not move Allah. It moves the person making it.

So Which Is It?
Both, and the two statements sit together more easily than they first appear.
Making a vow is discouraged, because it mistakes the arrangement. It treats an outcome as something to be bought, and it offers Allah a trade He has not asked for. Nothing you promise changes what has been decreed.
Keeping a vow is praised, because once words have been spoken to Allah, they are owed. The praise in the Qur'an is for the keeping, not for the making.
The practical conclusion is plain enough. If you want to give, give. If you want something, ask for it. Do not try to make one conditional on the other.
Once Made, It Binds
A vow to do something good must be kept. The Prophet ﷺ said that whoever vows to obey Allah should obey Him.
A vow to do something wrong must not be kept. He said in the same breath that whoever vows to disobey Allah should not disobey Him. A vow does not make a forbidden thing permissible, and there is no fulfilment of a vow in disobedience.
A vow over something you do not own is not binding. You cannot pledge what is not yours to give.
Where it genuinely cannot be fulfilled, scholars direct that the expiation for a broken oath is paid instead - feeding or clothing ten poor people, or freeing a person, or, failing those, fasting three days. The detail is on the Kaffarah page.
One point is agreed across the schools and worth stating plainly: a vow is made to Allah alone. It is an act of worship, and acts of worship are not directed elsewhere.
Vows and Charity
This is where the term reaches a charity, and there are three things worth knowing.
Vow money is not your Zakat. They are separate obligations and one does not discharge the other. Someone who vowed to give a sum and then counts it against their annual Zakat has paid one of the two.
Nor is it ordinary Sadaqah. Voluntary charity is given freely. A vow already owes the money. Giving it is discharging a debt rather than making a gift - which does not reduce its worth, but does mean you cannot change your mind about it.
Say what you mean when you make one. Vague vows cause real difficulty afterwards. Someone who said I will give a lot has to work out what that obliges, and scholars generally fall back on what the person intended or on what would ordinarily be understood by the words. Specific is easier to keep.
If you are giving vow money to a charity, say so. It should go where you pledged it, and a well-run organisation will want to know.

Frequently Asked Questions
No. Zakat is an annual obligation on wealth with its own rate, threshold and categories of recipient. A vow is a separate promise you made. Fulfilling one does nothing for the other, and someone who treats a vowed payment as their Zakat still owes their Zakat.
If it is genuinely beyond you, the expiation for a broken oath is paid in its place rather than the vow simply lapsing. Where the difficulty is temporary rather than permanent, most scholars would say wait and fulfil it when you can. Ask about the particular case rather than deciding alone.
Possibly not. Scholars distinguish a deliberate pledge from words that slipped out - an exclamation in a moment of distress is treated differently from a considered promise. Intention matters here, and if you are genuinely unsure what you meant at the time, that is worth describing to someone who can advise.
Then work from what you intended when you said it. If you cannot recall intending any particular figure, scholars generally direct you to what the words would ordinarily mean, erring on the generous side. This is the most common difficulty with vows and the easiest to avoid.
Just to give. The Prophet ﷺ discouraged vowing precisely because it offers nothing a person could not simply do, and risks treating Allah's decree as negotiable. Charity given freely carries every reward a vowed charity does, without binding you to anything.

So Which Is It?
Both, and the two statements sit together more easily than they first appear.
Making a vow is discouraged, because it mistakes the arrangement. It treats an outcome as something to be bought, and it offers Allah a trade He has not asked for. Nothing you promise changes what has been decreed.
Keeping a vow is praised, because once words have been spoken to Allah, they are owed. The praise in the Qur'an is for the keeping, not for the making.
The practical conclusion is plain enough. If you want to give, give. If you want something, ask for it. Do not try to make one conditional on the other.
A vow to do something good must be kept. The Prophet ﷺ said that whoever vows to obey Allah should obey Him.
A vow to do something wrong must not be kept. He said in the same breath that whoever vows to disobey Allah should not disobey Him. A vow does not make a forbidden thing permissible, and there is no fulfilment of a vow in disobedience.
A vow over something you do not own is not binding. You cannot pledge what is not yours to give.
Where it genuinely cannot be fulfilled, scholars direct that the expiation for a broken oath is paid instead - feeding or clothing ten poor people, or freeing a person, or, failing those, fasting three days. The detail is on the Kaffarah page.
One point is agreed across the schools and worth stating plainly: a vow is made to Allah alone. It is an act of worship, and acts of worship are not directed elsewhere.
This is where the term reaches a charity, and there are three things worth knowing.
Vow money is not your Zakat. They are separate obligations and one does not discharge the other. Someone who vowed to give a sum and then counts it against their annual Zakat has paid one of the two.
Nor is it ordinary Sadaqah. Voluntary charity is given freely. A vow already owes the money. Giving it is discharging a debt rather than making a gift - which does not reduce its worth, but does mean you cannot change your mind about it.
Say what you mean when you make one. Vague vows cause real difficulty afterwards. Someone who said I will give a lot has to work out what that obliges, and scholars generally fall back on what the person intended or on what would ordinarily be understood by the words. Specific is easier to keep.
If you are giving vow money to a charity, say so. It should go where you pledged it, and a well-run organisation will want to know.

Frequently Asked Questions
No. Zakat is an annual obligation on wealth with its own rate, threshold and categories of recipient. A vow is a separate promise you made. Fulfilling one does nothing for the other, and someone who treats a vowed payment as their Zakat still owes their Zakat.
If it is genuinely beyond you, the expiation for a broken oath is paid in its place rather than the vow simply lapsing. Where the difficulty is temporary rather than permanent, most scholars would say wait and fulfil it when you can. Ask about the particular case rather than deciding alone.
Possibly not. Scholars distinguish a deliberate pledge from words that slipped out - an exclamation in a moment of distress is treated differently from a considered promise. Intention matters here, and if you are genuinely unsure what you meant at the time, that is worth describing to someone who can advise.
Then work from what you intended when you said it. If you cannot recall intending any particular figure, scholars generally direct you to what the words would ordinarily mean, erring on the generous side. This is the most common difficulty with vows and the easiest to avoid.
Just to give. The Prophet ﷺ discouraged vowing precisely because it offers nothing a person could not simply do, and risks treating Allah's decree as negotiable. Charity given freely carries every reward a vowed charity does, without binding you to anything.