Is the congregational prayer in the mosque waived for an elderly father afflicted with forgetfulness and embarrassment? Is he to be held accountable for his speech, insults, and curses? Is it preferable for me to pray with him at home rather than praying congregational prayers in the mosque? How can I please him and earn his righteousness? Is there a specific supplication that can be repeated for him?

The intellect is the basis of religious obligation (taklif shar'i). Thus, whoever is aware of their actions is bound by religious duties (fara'id) and will be held accountable for prohibitions (muharramat). If your father is aware of his actions, then he must observe prayer (salat), and he should be advised gently if he neglects it or utters anything that contradicts Islamic law (Shari'ah).

It is permissible to combine congregational prayer in the mosque with praying with your father, or to miss congregational prayer in the mosque to pray with him if there is an excuse, such as nursing a family member.

To gain your father's pleasure: Show him dutifulness (birr) and kindness, obey him in what is good, be patient with any harm he may cause, and make abundant supplication for him.

Closing the door on your father at night and preventing him from going out is permissible if it is out of fear that harm may befall him.