Musnad Ahmad 27:1149

Nafi‘ said: That ‘Abdullah ibn ‘Umar narrated to him, "That the Messenger of Allah (ﷺ) prayed beyond al-‘Arj, while you are going, at a distance of five miles from al-‘Arj, in a mosque at a hillock. At that mosque are two or three graves, upon the graves is a heap of stones, on the right side of the road, near the landmarks of the road, between those landmarks." ‘Abdullah used to depart from al-‘Arj after the sun had declined at midday, and he would pray the Dhuhr prayer in that mosque.