Definition of miserliness according to Islamic teachings
Question

When is a man being stingy towards his wife and children according to Islamic teachings? Some people think that I am doing what is obligatory, and others think that I am somewhat miserly.
Praise be to Allah.Firstly:
Miserliness is a blameworthy characteristic, and what disease can be worse than miserliness? The scholars have differed concerning its definition.
Ibn Muflih (may Allah have mercy on him) said:
The scholars mentioned a number of opinions concerning the definition of miserliness, including the following:

Withholding zakaah; the one who gives it cannot be described as a miser.
Withholding obligatory spending, such as zakaah and maintenance. Based on that, if a person gives zakaah but withholds other kinds of obligatory spending, then he is regarded as miserly. [This view was favoured by Ibn al-Qayyim and others].
Doing that which is obligatory in terms of spending as well as (extra) acts of generosity and charity. If a person does not do the latter, then he is regarded as miserly. [This view was favoured by al-Ghazali and others]. End quote from al-Aadaab ash-Shar‘iyyah (3/303).

Ibn al-Qayyim (may Allah have mercy on him) said:
The miserly person is the one who withholds what he is required to give. The one who gives all that he is obliged to give cannot be called miserly; rather the miserly person is the one who withholds what is due from him to give.
End quote from Jalaa’ al-Afhaam (p. 385). Al-Qurtubi (5/193) said something similar.
Al-Ghazali (may Allah have mercy on him) said:
The miserly person is the one who withholds when he should not withhold, either according to Islamic teaching or according to common decency. This is not something that can be quantified.
End quote from Ihyaa’ ‘Uloom ad-Deen (3/260).
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said something similar:
Miserliness is withholding what is obligatory and what should be given.
End quote from Sharh Riyaadh as-Saaliheen (3/410).
Secondly:
A man is obliged to spend on his wife and children on a reasonable basis. That includes providing food, drink, clothing, shelter, and everything the wife and children need that is essential, such as medical treatment, education and so on.
That spending should be according to the husband’s means and his financial situation, because Allah, may He be exalted, says (interpretation of the meaning):
“Let a man of wealth spend from his wealth, and he whose provision is restricted - let him spend from what Allah has given him. Allah does not charge a soul except [according to] what He has given it”
[at-Talaaq 65:7].
The obligatory spending on one’s wife and children varies according to how well off or otherwise the husband is. Whoever is well off should spend as one who is well off spends on his wife and children; if he imposes constraints on them in terms of spending, then he is regarded as miserly, because he is failing to do what is enjoined upon him.
The one who is not well off should spend as one who is not well off spends. Whoever is of moderate means should spend according to his situation, and Allah does not burden any soul with more than He has given it.
There is no set limit for that according to Islamic teaching; rather reference should be made to what is customary among the people.
See the answer to question no. 3054.
Conclusion:
The one who withholds his wealth from his wife and children when he should spend on them is a miser.
And Allah knows best.