Musnad Ahmad 27:2002

Hammad narrated to us, from Abdullah, from Nafi’, who said: Ibn Umar used to spend the night at Dhu Tuwa. When he reached the morning, he would perform ghusl (ritual bath), and he would command those who were with him to perform ghusl. He would enter [Makkah] from the upper pass, and when he exited, he would exit from the lower pass. He claimed that the Prophet, peace and blessings of Allah be upon him, used to do that.