So the Mosque of Arafat gives him knowledge of himself, so that he may have that as a ladder to knowing his Lord, for

He who knows himself knows his Lord

To whom he prostrates, and knowledge requires one thing in transgression, it is his attachment, i.e. attachment. The servant’s knowledge and knowledge of the oneness of God in particular. If he did not say “Arafah” and said something that indicates knowledge, as Arafah indicated knowledge, we would not make it related to oneness, but we would make it something else.