Musnad Ahmad 27:1151

Nafi’ said: Abdullah ibn Umar narrated to him, "That the Messenger of Allah (peace and blessings of Allah be upon him) used to stay at Dhu Tuwa and spend the night there until he performed the morning prayer, when he arrived in Makkah. The place where the Messenger of Allah (peace and blessings of Allah be upon him) prayed was on a rugged hillock, not in the mosque that was built there later, but below that, on a rough, rugged hillock."