Answered by Shaykh Faraz Rabbani
Can I spy on my younger brother by keeping logs of his internet use, chat sessions, and so on, if I think he may be accessing haram sites and the like?
Walaikum assalam wa rahmatullah,
It is not right to spy.
Rather, use positive preventative means, the best of which are encouraging the person towards the company of practicing Muslims, and spending quality time with them.
And Allah alone gives success.
Wassalam,
Faraz Rabbani