Is the fast of one who masturbated intentionally during a Ramadan night valid if they only performed ghusl at the time of Duha? And will the fast of the Day of Arafah be accepted after that?

Masturbation is forbidden, and Ramadan (definition) is a month of worship, not a month of sin and disobedience. The fast of the following day is valid if masturbation occurred at night, but one must perform ghusl (definition) (ritual bath) for prayer, and it is not permissible to delay it or to pray in a state of janabah (definition) (ritual impurity), as both are forbidden. The fast of Arafah expiates the sins of two years, and good deeds remove evil deeds. What is obligatory is sincere repentance and not returning to the sin.