Is it permissible for a father to control the life of his 20-year-old son, to beat him, and to insult him daily over minor matters? And what is the age of maturity, and when does a father's control over his son end?

When a child reaches maturity ( رشيدًا ), they are no longer subject to custody ( حضانة ) and have the right to live independently. However, they are still obligated to show filial piety to their parents. It is commendable for them not to live separately from their parents and not to cease their dutifulness towards them.

Scholars have differed regarding a father disciplining his adult child through striking and verbal abuse. Some view it permissible to discipline an adult, even if married, while others deem it impermissible for a father to punish an adult, even if the adult is foolish.

According to those who permit it, such discipline should be a last resort, used only when necessary and with hope of benefit, while adhering to the guidelines of discipline.

Regardless of the parent's situation, they have a right over their child, and obedience to them is obligatory, unless they command an act of disobedience or something that harms the child. Filial piety towards parents is among the greatest causes for Allah's pleasure and entry into Paradise.