He has no right in beating his sister like this! Only her father has the right to discipline his daughter and not by using excessive force like this.
He has the right to force her to wear hijab by not allowing her to leave the house. As for prayers, if she oversleeps, he should advise her, wake her up on time and remind her of Allah.

my friend has been beating her sister in the recent weeks for not wearing hijab in the house and waking up late….I would like u to teach me how I can advise him…coz I fear he may end up hurting her