Reference: al-Bid’u wal-Muhdathaat wa maa laa asla lahu – Page 404
Question: We have noticed some pilgrims are unable to pray in Masjid Namirah [on the 9th day of Dhul-Hijjah, the Day of ‘Arafah]. They pray where they are, so one of them stands and delivers a khutbah and then leads the prayer, just like in a masjid. So, is it permissible to have two [or more] khutbahs in ‘Arafah?
Response: There is only one khutbah on the Day of ‘Arafah, which is given by the Imaam of the Muslims or his deputy, in one place and that is Masjid Namirah. It is not legislated for all pilgrims, rather the remainder of the pilgrims who are unable to attend the khutbah should combine and shorten the Zhuhr and ‘Asr salaahs at the time of Zhuhr [and not delay it until ‘Asr], without a khutbah. That, which these people do, as the questioner mentions, is considered an innovation and it is not permissible. Instead, it is obligatory to leave this and prevent this from being done and also attempt to listen to the khutbah via the speakers [placed outside the masjid for those unable to enter the masjid].
