He gives his family money to buy luxuries and borrows from his wife

Praise be to Allah.

Firstly: 

People often mention in their questions the phrase “the opinion of sharee’ah” or “ the opinion of the deen (religion)”. These phrases are not correct in their meanings, and it is better for a Muslim to avoid them. 

Shaykh Bakr Abu Zayd (may Allaah preserve him) said: 

Among the incorrect phrases is “the opinion of the deen (religion)”. The word ra’y (opinion) is based on pondering and thinking. Other such phrases include “the opinion of Islam” and “the opinion of sharee’ah”. These are widespread phrases in the late 14^th Hijri century, but they are unacceptable according to sharee’ah, because opinions vary and may be wrong or right, so it is clear that this word cannot apply to that which Allaah has decreed in His Book and the Sunnah of His Messenger (blessings and peace of Allaah be upon him), because that is the religion of Islam – “Truly, the religion with Allaah is Islam” [Aal ‘Imraan 3:19]. And Allaah says (interpretation of the meaning): “It is not for a believer, man or woman, when Allaah and His Messenger have decreed a matter that they should have any option in their decision” [al-Ahzaab 33:36].

So with regard to that which Allaah has legislated for His slaves, it should be said: the ruling of Allaah, or His command, prohibition, decree and so on. With regard to something that is like that, the word “opinion” cannot be used, because opinion is based on speculation and may be right or wrong. 

But if the ruling stems from ijtihaad, it cannot be called the “opinion of the deen”, rather it is to be called the opinion of the mujtahid or scholar, because when there are differences of opinion concerning an issue of Islam, then the truth lies in one of these opinions. See an important discussion in the book Tanweer al-Afhaam li ba’d Mafaaheem al-Islam by Shaykh Muhammad ibn Ibraaheem Shaqrah, p. 61-73. End quote. 

Mu’jam al-Manaahi al-Lafziyyah, p. 223, 224, 1^st edition. 

Secondly: 

Children should spend on their parents, and this obligation is proven in the Qur’aan and Sunnah and by scholarly consensus. See the answer to question number 111892. 

This obligatory spending on the parents is subject to conditions, one of which is that the son should be able to afford spending on them and the parent should be in need because of incapability, poverty or not being able to earn a living. 

This husband should realise that his reward with Allaah will be great if he is spending on his needy parents to provide necessary maintenance, even if that means he has to borrow money. But if his parents are not in need of obligatory maintenance, and he is spending on them to buy them luxury items, then he should look after himself and he should not incur debts that are not necessary or due to urgent need, because the matter of debt is serious before Allaah. It was narrated in a saheeh report that the Prophet (blessings and peace of Allaah be upon him) said: “The martyr will be forgiven everything except debt.” So how about the one who meets Allaah when he has not been killed for His sake? 

Yes, if he has surplus money and he wants to make life comfortable for his parents by spending on permissible but non-essential things, then he will be treating them kindly and not mistreating himself. But if he does that with the wealth of others -- his wife or anyone else -- then he is mistreating himself because he is taking on something that he cannot bear. 

Based on that, he should apologise to them in the kindest words and explain that he is not able to give them what they want, and he should promise them that if he gets money that is surplus to the needs of his children and his wife, then he will give to them. 

Allaah says (interpretation of the meaning):

“And if you (O Muhammad صلى الله عليه وسلم) turn away from them (kindred, poor, wayfarer, whom We have ordered you to give their rights, but if you have no money at the time they ask you for it) and you are awaiting a mercy from your Lord for which you hope, then, speak unto them a soft, kind word (i.e. Allaah will give me and I shall give you)”

[al-Isra’ 17:28]. 

Ibn Katheer (may Allaah have mercy on him) said: 

i.e., if your relatives and those to whom We have enjoined you to give ask you for something, and you do not have anything and you turn away from them because you cannot afford to spend, “then, speak unto them a soft, kind word” meaning, make them a promise, in kind and gentle words, that when the provision of Allaah comes, we will give you some, if Allaah wills. End quote.

Tafseer Ibn Katheer, 3/52.