Is the father considered sinful for persistently praying for cancer upon his two daughters in secret, due to their rejection of the hijab and their mockery of it?

A father should not curse his daughters with illnesses; rather, he should remind them of Allah and the prohibition of immodest display and adornment (Sufur and Tabarruj), and supplicate for their righteousness and steadfastness. A group of scholars has deemed this forbidden, and it is disliked for a person to curse themselves, their children, or their wealth. What is obligatory upon him is to command them to observe the hijab and cover, and to forbid them from immodest display and adornment.