What is the ruling of Islamic law regarding a father who favors some of his children in inheritance on the pretext of their working with him, and deprives others because they are government employees, and will his supplication against them be answered?

What the father did by registering the land in the name of some of his children falls into one of two categories:

The first category: That he gifted it to them during his lifetime. This is impermissible, because a parent must equalize between their children in gifts and donations, unless there is a legitimate reason for preference, such as need, illness, or preoccupation with seeking knowledge. In this case, the father must reclaim the land or give the other children an equivalent amount.

The second category: That he bequeathed it to them after his death. This is a bequest to an heir, which is invalid unless the other heirs agree to it.

As for a parent's prayer against their child, it is answered if the child is disobedient or unjust to their parent. However, if the child is not so, then the parent's prayer against them will not be answered because it would be considered sinful and aggressive. We advise the questioner to be dutiful to his father and treat him kindly in all circumstances.