Praise be to Allah.
Riba is a major sin and a serious crime, and the one who deals in it is warned of a declaration of war from Allah and His Messenger, loss of blessing, and curses. A sin that is like this is something that one should flee from and keep far away from it by all possible means.
Allah, may He be exalted, says (interpretation of the meaning):
“Allah will destroy Riba (usury) and will give increase for Sadaqat (deeds of charity, alms, etc.) And Allah likes not the disbelievers, sinners”
“O you who believe! Fear Allah and give up what remains (due to you) from Riba (usury) (from now onward), if you are (really) believers.
And if you do not do it, then take a notice of war from Allah and His Messenger but if you repent, you shall have your capital sums. Deal not unjustly (by asking more than your capital sums), and you shall not be dealt with unjustly (by receiving less than your capital sums)”
Muslim (1598) narrated that Jaabir (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) cursed the one who consumes riba and the one who pays it, the one who writes it down and the two who witness it, and he said: they are all the same.
The interest that is paid by riba-based banks is the very essence of riba. If a person is compelled by necessity to keep his money in a riba-based bank, then he should keep it in a current account. If a person has repented from dealing in riba and he receives any interest payments, it is obligatory for him to get rid of it by spending it on charitable causes, and it is not permissible for him to keep it for himself.
Withholding zakaah is also a major sin, but despite that it is not haraam to interact with a person who withholds zakaah or to accept his gift, because zakaah is a debt that he owes, but his wealth is not like the wealth that was seized by force or stolen, which it is haraam to take for the one who knows that it is stolen.
The correct scholarly view is that that which is haraam because of the way in which it is acquired is only haraam for the one who acquired it in that manner, and it is not haraam for the one who takes it from him in a way that is permissible, such as receiving it as a gift and the like.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said:
Some of the scholars said: With regard to that which is haraam because of the way in which it is acquired, the sin thereof is borne only by the one who acquired it in that manner, not by the one who takes it from him in a permissible manner. This is in contrast to that which is haraam in and of itself, such as alcohol, property that was seized by force, and the like. This is a strong view, based on the evidence that the Messenger (blessings and peace of Allah be upon him) bought food from the Jews for his family, and he ate from the sheep that was given to him as a gift by the Jewish woman in Khaybar, and he accepted the invitation of a Jewish man, and it is well-known that most of the Jews take riba (usury) and deal in haraam wealth. This view may be further strengthened by the fact that the Prophet (blessings and peace of Allah be upon him) said concerning the meat that was given in charity to Bareerah (and she gave some of it to the Prophet (blessings and peace of Allah be upon him)): “For her it is charity and for us it is a gift.”
End quote from al-Qawl al-Mufeed ‘ala Kitaab at-Tawheed (3/122)
He also said:
With regard to that which is haraam because of the way in which it is acquired, such as that which is taken by way of bribes, or by way of riba, or by way of lying, and the like, it is haraam for the one who acquired it in that manner, but it is not haraam for the one who acquires it from him in a permissible manner. This is supported by the fact that the Prophet (blessings and peace of Allah be upon him) used to deal with the Jews even though they used to consume haraam wealth and take riba. This indicates that it is not haraam for anyone other than the one who acquired it by haraam means.
End quote from Tafseer Soorat al-Baqarah (1/198)
Based on that, if a father buys an apartment for his son with riba money, there is nothing wrong with the child making use of it, because the sin of riba is only on the one who acquired it in that manner.
It may be said to the son in this case: If your refusal to live in this apartment will not have any impact by making your father give up riba – rather it will only make him angry and sad, and he will carry on with that – then there is nothing wrong with you getting married and living in that apartment.
If a person deals in riba then repents to Allah, may He be exalted, if the riba wealth is still there, then he has to rid himself of it, but if he has used it up and consumed it, then he does not have to do anything with regard to it.
If he put that money into accommodation that he needs, he does not have to sell it and get rid of the riba, unless he chooses to do so himself, which is undoubtedly better. This is by way of making it easy to repent for those who have committed sins, because if they were to be told: Get rid of whatever you possess of everything that you purchased by means of riba, that would cause them hardship and would cause many of them to delay repentance.
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said: A man may live for a long time without praying or giving zakaah, or fasting, and not caring how he acquires his wealth, whether it is from halaal or haraam sources, and not following the guidelines on marriage and divorce, and so on, so he is living in a state of ignorance, apart from the fact that he claims to be a Muslim. When Allah guides him and has mercy upon him by enabling him to repent, if he were obliged to make up all that he had missed of obligatory duties, and if he were to be ordered to return everything that he had acquired of wealth, and to give up everything that he loves, and so on, repentance would become a punishment for him, and in that case disbelief would be dearer to him than Islam, which he has identified with, because repentance from disbelief would be a mercy but repentance when he is already a Muslim would be a punishment. I know some righteous people who wished that they had been disbelievers so that they could become Muslims and be forgiven for all their previous misdeeds, because repentance for them was impossible or too difficult, according to what they had been told about repentance and what they believed about it. Moreover, this deters most of those who commit evil deeds from repenting, and it is more like causing the people to despair of the mercy of Allah, and placing a heavy burden on those who repent, who are the loved ones of Allah, for Allah loves those who repent and He loves those who purify themselves, and Allah rejoices over the repentance of His slave more than the one who finds his property in which is his means of survival after having despaired of ever finding it again.
End quote from Majmoo‘ al-Fataawa (22/21)
Our advice to this son is to continue honouring his father and reminding him of the prohibition on riba and the obligation to hasten to give it up. He should also hasten to get married so long as he is able to do so, so as to protect himself and guard against temptation.
We ask Allah, may He be exalted, to set straight the affairs of all.
And Allah knows best.