Praise be to Allaah.
It is obligatory to obey parents except in matters that are
sinful, because the Prophet (blessings and peace of Allah be upon him) said:
“There is no obedience to any human being if it involves sin; obedience is
only in that which is right and proper.”
Narrated by al-Bukhaari, 7257; Muslim, 1840.
And he said: “There is no obedience to any human being if it
involves disobedience of Allah.”
Narrated by Ahmad, 1098
Obedience to parents is obligatory upon the child in matters
that are beneficial to them and do not harm the child. With regard to that
in which there is no benefit for them or there is harm for the child, he is
not obliged to obey them in that case.
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him)
said in al-Ikhtiyaaraat (p. 114): The individual is obliged to obey
his parents in matters that are not sinful, even if they are evildoers. …
This has to do with that which is beneficial for them and not harmful for
him. End quote.
With regard to what your mother said about it being
obligatory for you to obey her, that is true and it is enjoined by Allah,
may He be exalted. But if there is a conflict between the command of Allah,
may He be exalted, and the command of the mother or father in that they
command you to do something that is contrary to the command of Allah, the
believer has no doubt that what he should do is give precedence to the
command of Allah, may He be exalted. Hence the Prophet (blessings and peace
of Allah be upon him said:
“There is no obedience to any human being if it involves sin;
obedience is only in that which is right and proper.”
Narrated by al-Bukhaari, 6830; Muslim, 1840.
It says in al-Mawsoo‘ah al-Fiqhiyyah, 28/327
Obedience to other people – those to whom obedience is
obligatory – such as parents, the husband and those in authority – is
restricted to matters that do not involve disobedience or sin, because there
is no obedience to any human being if it involves disobedience of the
Creator. End quote.
Shaykh al-Fawzaan (may Allah preserve him) said:
Women are enjoined to obey Allah, may He be glorified and
exalted, and they are enjoined to obey their husbands and parents, within
the framework of obedience to Allah.
But if obeying a person such as one’s father or husband
involves disobedience of the Creator, this is not permissible, because the
Prophet (blessings and peace of Allah be upon him) said: “Obedience is only
in that which is right and proper)” (narrated by al-Bukhaari) and he
(blessings and peace of Allah be upon him) said: “There is no obedience to
any created being if it involves disobedience to the Creator” (narrated by
Ahmad). End quote.
Al-Muntaqa min Fataawa al-Shaykh al-Fawzaan,
1/265, 266, Question no. 161
Based on that, it is haraam for you to take out a riba-based
loan in order to buy a house – as you know, may Allah bless you – so you
should let your mother know that it is haraam for you to obey her in that,
and that her anger with you is as nothing before Allah, may He be exalted.
But you should treat her kindly because of the great rights that she has and
her status before Allah.
You have to be gentle with her and try to convince her that
no matter how much you may gain from something haraam, there is no barakah
in it and it will lead to bad consequences.
We ask Allah to make good easy for you where ever you are.
And Allah knows best.