the mountain of ‘Arafaat which is known to the people as Jabal al-Rahmah. It was not his way to climb this mountain during Hajj or to take it as a ritual

Is there any specific reward for climbing up Jabal al-Rahmah on the
day of 'Arafah and praying there?.
Praise be to Allaah.
It is not proven that the Prophet (blessings and peace of Allah be
upon him) encouraged climbing the mountain of 'Arafaat which is known
to the people as Jabal al-Rahmah. It was not his way to climb this
mountain during Hajj or to take it as a ritual. He (blessings and
peace of Allah be upon him) said: "Learn from me your rituals (of
Hajj)." The way of the Rightly Guided Caliphs and all the Sahaabah was
like that of the Prophet (blessings and peace of Allah be upon him),
and the same was true of those who followed in their footsteps. They
did not climb up to this mountain during their Hajj and they did not
take it as a ritual, following the example of the Messenger of
Allah(blessings and peace of Allah be upon him). What is proven is
that he(blessings and peace of Allah be upon him) stoodat the foot of
this mountain at the large rocks and he said: "I have stood here and
all of 'Arafah is the place of standing, and avoid the valley of
'Aranah. Hence many of the scholars, such as Imam al-Nawawi, Shaykh
al-Islam Ibn Taymiyah and Shaykh Siddeeq Khan, said: Climbing this
mountain during Hajj as if it were a ritual is an innovation. The
Prophet (blessings and peace of Allah be upon him) said: "Whoever does
an action that is not part of this matter of ours will have it
rejected." It was not his practice to offer any naafil prayer in the
standing at 'Arafah; rather he limited it to praying Zuhr and 'Asr in
Masjid Namirah, joining and shortening the prayer. He did not take any
place for prayer in what is called Jabal al-Rahmah in which those who
climb this mountain should offer naafil or obligatory prayers on the
day of 'Arafah. Rather, after praying Zuhr and 'Asr, hebusied himself
with remembering Allah (dhikr), reciting tasbeeh ("Subhaan Allah"),
tahleel (Laa ilaaha ill-Allaah), tahmeed (al-hamdu Lillah), takbeer
(Allahu akbar) and Talbiyah, calling upon his Lord and beseeching Him,
until the sun set. So taking a place on this mountain in which to pray
by those who climb up it is an innovation introduced by the ignorant.
And Allah is the source ofstrength; may Allah send blessings and peace
upon our Prophet Muhammad and his family and Companions. End quote.
Standing Committee for Academic Research and Issuing Fatwas.
Shaykh Ibraaheem ibn Muhammad Aal al-Shaykh, Shaykh 'Abd al-Razzaaq
'Afeefi, Shaykh 'Abd-Allaah ibn Ghadyaan, Shaykh 'Abd-Allaah ibn
Munayyi'
Fataawa al-Lajnah al-Daa'imah, 11/206-208
Shaykh Ibn Uthaymeen (may Allah have mercy on him) said:
Climbing up the mountain of 'Arafaat is not something that is
prescribed in Islam; rather if the people take it as an act of worship
it is an innovation; it is notpermissible for people tobelieve that
this is an actof worship or to do it onthe basis that it is an act of
worship. The Messenger (blessings and peace of Allah be upon him) was
the keenest of all people to do good and was the most effective of all
people in conveying the message and he was the most knowledgeable of
all people of the religionof Allah. He did not climbthis mountain or
instructanyone to do so, and he did not approve of anyone climbing it
as faras I know. Based on that,climbing this mountain is not
prescribed; rather the Messenger of Allah (blessings and peace of
Allah be upon him) said, when he stood behind iton the eastern side:
"I have stood here and all of 'Arafah is the place of standing." It is
as if he (blessings and peace of Allah be upon him) was indicating
that each person should stand in his own spot and not push and shove
in order to reach the place wherethe Messenger (blessingsand peace of
Allah be upon him) stood.