Brother-in-law has no authority over brother's wife
30-5-2016 | IslamWeb
Question:
Assalaamu alaykum. My question is: can I stop my sister-in-law from going to my uncle's house (mother's brother) by herself as it is creating a lot of confusion in the family? She is my eldest sister-in-law among four brothers, and I am the youngest son-in-law to her, but my second brother says that I cannot tell her this as I have no say in her life. However, I argued that if she wants to go, then she should go with our mother as her relation starts with my mother. This situation only started when my uncle divorced his second wife, and my sister-in-law was very close to her. After the divorce, my sister-in-law has been in touch with her, and my uncle's first wife's sons think that she is secretly telling my ex-aunty about whatever happens there. I have discussed this with my elder brother also, but he has not said anything to his wife. For that reason, I said it to her in front of my mother and sisters. Do I have the right to tell her this or not?
Answer:
All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger.
You have no right to prevent your brother's wife from going to your uncle's house; you have no guardianship or authority over your sister-in-law to prevent her from doing so. It is also impermissible for you to accuse her of disclosing your uncle's secrets to his ex-wife without clear evidence. Islam forbids thinking ill of others; Allaah, The Exalted, says (what means): {O you who have believed, avoid much (negative) assumption. Indeed, some assumption is sin...} [Quran 49:12]
If such accusations are proven to be correct, then you should give her advice and remind her of Allaah. If she does not stop, then her husband should strictly prevent her from going there, as Allaah gave him authority over her; Allaah, The Exalted, says (what means): {Men are in charge of women by (right of) what Allaah has given one over the other and what they spend (for maintenance) from their wealth...} [Quran 4:34] Moreover, Ibn 'Umar 
said that the Prophet, sallallaahu ʻalayhi wa sallam, said, "All of you are guardians and are responsible for your wards ... the man is a guardian and responsible for his family..." [Al-Bukhari and Muslim]
If such accusations are correct, then your uncle should also be firm with her and prevent her from entering his house so as to prevent her from sowing seeds of discord and fueling grudges.
Allaah knows best.