Praise be to Allah.
One of the things concerning which there can be no doubt is that the marital bedroom is particularly private; it is the wife’s chamber and private space, the innermost part of her house, where she takes off her clothes and is alone with her husband, which is something that she cannot do anywhere except in this place.
What makes this place even more private is that it is where she keeps her private clothes, cosmetics and adornments, and things that have to do with intimacy between husband and wife, which no one else should see, as they are regarded as being among the most private aspects of the marital relationship.
What we have mentioned is the basic principle, and no one should go against it, but there may be specific circumstances which dictate allowing a relative to enter this private space, either because the house is small, or because they need to use the room for one of the women to sleep in, because it is more private than other parts of the house, or for some other reason, but that permission is subject to certain conditions:
1.That there should be a real need for that
2.That the underwear of the couple should not be visible, or anything else that may cause embarrassment if it is seen
3.That the person to whom permission is given to enter should be trustworthy, lest he mess about with private things in the room or tell others about it
4.That the husband should give permission for this person to enter. If he refuses then that should be heeded and one should not go against that. Similarly, the husband should not allow anyone to enter his wife’s bedroom if she dislikes that, unless it cannot be avoided, and the one who enters should be trustworthy, such as his mother or sister and so on, and he should ask his wife for permission and put her mind at rest.
Whatever the case, the conditions that we have mentioned here are subject to ijtihaad, and the purpose of them is to protect the privacy of the family members, with particular attention to the marital relationship, and protect it from being messed about with or from breaches of confidentiality and disclosure of secrets.
Muslim (1218) narrated that Jaabir ibn ‘Abd-Allaah (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Fear Allaah with regard to women, for you have taken them as a trust from Allaah, and intimacy with them has become permissible to you by the word of Allaah. Your rights over them are that they should not allow anyone whom you dislike to sit on your furniture. If they do that, then hit them, but in a manner that does not cause injury or leave a mark.”
Shaykh Muhammad ibn Saalih al-‘Uthaymeen (may Allaah have mercy on him) said: The Prophet (peace and blessings of Allaah be upon him) explained their rights and duties, and said: “Your rights over them are that they should not allow anyone whom you dislike to sit on your furniture” meaning, they should not allow anyone to enter upon them where they sleep or elsewhere, if you dislike people sitting on the furniture in your house. It is as if – and Allaah knows best – he was coining a similitude, meaning that they should not honour anyone whom you dislike. This is going against you by honouring one whom you dislike, by allowing him to sit on the furniture, or offering food to them, and so on. End quote.
Sharh Riyaadh al-Saaliheen (3/126)
With regard to believing that if someone sleeps in the marital bed that will cause problems between the couple, this is a jaahili (ignorant) belief and a myth that the Muslim should be above accepting because of his belief in Tawheed. There is nothing in Islam that supports this idea, and there is nothing in real life that confirms it.
With regard to your problems with your husband and his mother, this matter needs to be dealt with wisely and properly by you. Seek to earn your husband’s pleasure by being kind towards his mother, and seek to earn his mother’s love by dealing with her kindly, giving her gifts, and speaking nicely to her, because a kind word and good treatment win hearts. Seek reward from Allaah for putting up with annoyance from your husband’s mother and seek to please your husband; perhaps Allaah will create love and compassion between you and her. Seek the help of Allaah to fulfil your husband’s rights and to be patient in putting up with difficulties, and expect ease after hardship, and relief after difficulty.
For reasons why the husband’s mother may not like the wife, and ways of dealing with the problems that result from that, please see the answer to question no. 84036.
And Allaah knows best.