Is what the brother did by tearing his sister's tight clothing, after repeatedly warning her, in accordance with Sharia? Does Sharia give him this authority of deterrence? And what should he do when faced with the mother's support for the sister, while the father is helpless?

A sister wearing tight and eye-catching clothes that reveal her body's details is a form of tabarruj (display of adornment), which the Prophet (peace be upon him) warned against in the hadith: "There will be women who are clothed yet naked, inclining [to evil] and inclined [to it]. Their heads will be like the humps of leaning camels. They will not enter Paradise, nor will they smell its fragrance." This is a great error, and her parents should not have approved of it. The change should come through advice given with wisdom and beautiful admonition, not with harshness and violence, lest it lead to persistence [in error] and rebellion. For Allah, the Almighty, said: "And speak to him with gentle speech that perhaps he may be reminded or fear [Allah]," and He said: "So by mercy from Allah, [O Muhammad], you were lenient with them. And if you had been rude [in speech] and harsh in heart, they would have disbanded from about you."