Ruling on calling Mount ‘Arafah Jabal al-Rahmah

Shaykh Muhammad ibn ‘Uthaymeen (may Allaah have mercy on him) answered this question by
saying: 

I do not know of any basis for this name in
the Sunnah, i.e., that the mountain in ‘Arafah, by which the Prophet (peace and blessings of Allaah be upon him) stood, is called Jabal
al-Rahmah (the Mount of Mercy). Since there is no basis for that in the Sunnah, it should not be called by that name. Perhaps those who call it
thus realize that this is a great standing in which those who stand at ‘Arafah receive the forgiveness and mercy of Allaah, so they called it by
this name. But it is better not to use this name, rather it should be called Jabal ‘Arafah (Mount ‘Arafah), or the mountain by which the Prophet
(peace and blessings of Allaah be upon him) stood, etc.