What should I do about my children's failure to observe prayer in the mosque and at home, despite my advising and even hitting them, and am I sinful for leaving them due to their lack of responsiveness?

It is recommended to be patient in inviting one's children [to righteousness], and to emulate Noah, peace be upon him, who invited his people for a long time without despairing. One must continue advising them, even if they do not respond, for enjoining good and forbidding evil does not cease, even if it is thought to be ineffective. There is a great reward in continuing to offer sincere advice, and their hearts may change, leading them to guidance.