Is it permissible to take 25,0 Saudi Riyals from the National Guard, which is a salary for a period during which I did not work, and what should I do with it if it is not permissible?

The salary received for work not performed by its recipient is unlawful (haram (definition)). Seeking permission from the granting entity is not effective unless that entity is authorized to grant gifts without work. If this is not the case, the money must be returned to the granting entity. If that is impossible, it should be given as charity to the poor and needy, or spent on public welfare as a substitute for the state. If the recipient is poor and in need, he may benefit from it to the extent of his need, provided there was no negligence on his part or indulgence in delaying the return of the money.