Wife refusing to fulfil her duties towards her husband because he is not spending on her

Firstly:

It is obligatory for a man to spend on his wife, and your father did spend on her when he was able to, for twenty years, as you explained in your question.

According to Islamic teachings, your father is still regarded as spending on your mother, because spending on her has nothing to do with the issue of where he is getting the money from that he spends on her.

The other issue is that the sons’ spending on their mother is to be regarded as being like the father spending on her, because the Prophet (blessings and peace of Allah be upon him) said: “You and your wealth belong to your father.” Ahmad (6902); classed as sahih by al-Albani in al-Irwa’ (1625).

And the Prophet (blessings and peace of Allah be upon him) said: “The best food that you eat is what you earn by your own hands, and your children are part of your earnings.” At-Tirmidhi (1358); classed as sahih by al-Albani.

Shaykh Ibn Baz (may Allah have mercy on him) said: The father is obliged to spend on his wife, if her children cannot take care of her. But if her children are covering her expenses and they have been covering all her needs, then that is sufficient, because the children are his children too, and his rights over them are great. The Messenger (blessings and peace of Allah be upon him) said: “You and your wealth belong to your father.” So if they are covering their mother’s needs and spending on her, that is sufficient, praise be to Allah.

But if they are not covering her needs, and she is asking for maintenance, she has a choice: if she wishes, she may be patient, or if she wishes, she may say: Divorce me. She may ask for divorce if she cannot be patient, otherwise she should be patient. If her children spend on her and cover her needs, praise be to Allah, and there is no blame on the husband… If his children spend on her, then she has no right to complain or ask her husband to spend on her, because his children’s spending on her is like his spending on her. If they spend on her what is sufficient for her needs, praise be to Allah. If they do not spend on her and he does not spend on her either, then she may ask for divorce. (From the shaykh’s website.)

Based on that, so long as you and your brother are spending on her and covering her needs, she has no right after that to ask for more maintenance from your father, and he is entitled to all his rights over her in full.

Once this is established, then it becomes clear that your mother’s refusing intimacy on the grounds that the father is not spending on her is not permissible, and as a result she is regarded as defiantly disobedient and is sinning.

She must fear Allah, for this is a grievous sin. It is soundly narrated from the Prophet (blessings and peace of Allah be upon him), as is stated in the hadith of Abu Hurayrah (may Allah be pleased with him), that the Prophet (blessings and peace of Allah be upon him) said: “If a man calls his wife to his bed and she refuses to come, the angels will curse her until morning.” Narrated by al-Bukhari (3065).

According to another hadith, “There is no man who calls his wife to his bed and she refuses, but the One Who is in heaven will be angry with her, until he is pleased with her.” Narrated by Muslim (1436).

Secondly:

From your question, it seems that your father was not falling short with regard to your mother’s rights or your rights when he was able to spend on you. When his circumstances changed and he was no longer able to spend, your mother forgot his kindness. This is ingratitude towards the husband concerning which the Prophet (blessings and peace of Allah be upon him) warned the woman who does that of Hell. According to the hadith, the Prophet (blessings and peace of Allah be upon him) said: “I was shown Hell, and I saw that most of its inhabitants are women who are ungrateful (yakfurna).” It was said: Do they disbelieve (yakfurna) in Allah? He said: “They are ungrateful (yakfurna) to their husbands and are ungrateful for kind treatment. If you show kindness to one of them for a lifetime, then she sees something from you, she says: I have never seen anything good from you.” Narrated by al-Bukhari (29).

Ibn Battal (may Allah have mercy on him) said: This refers to the husband. Allah enjoined His Messenger to show gratitude for blessings. It says in the hadith: “He does not thank Allah who does not thank people.” Gratitude for the kindness of the husband comes under the heading of gratitude for the blessings of Allah, because every favour the husband does to his family is a blessing from Allah that He caused to come at his hands."(Sharh Sahih al-Bukhari by Ibn Battal (1/89).

What the hadith means is that they are denying kind treatment… This indicates that the one who denies the kindness of the one who was kind to him is blameworthy. Al-Karmani said: That is, you [women] deny the kind treatment of the husband and think little of whatever he gives you. We may understand from the warning of hellfire for being ungrateful and cursing a great deal that these are major sins. See: Sharh Ibn Majah by as-Suyuti, et al. (p. 289).

Hence it is important to advise your mother regarding this matter, and tell her that showing kindness to her husband is one of the means of a woman attaining the pleasure of Allah, and is one of the means of her attaining happiness in this world and the hereafter.

And Allah knows best.