Musnad Ahmad 27:1310

'Affan narrated to us, Sulaym ibn Akhdar narrated to us, 'Ubayd Allah narrated to us, from Nafi', who said: 'Abdullah ibn 'Umar used to perform *ramal* (a brisk, jogging walk) from the [Black] Stone to the [Black] Stone, and he would inform us that "the Prophet, peace and blessings of Allah be upon him, used to do that." 'Ubayd Allah said: So they mentioned to Nafi' that he [Ibn 'Umar] used to walk between the two corners. He said: "He would not walk except when he intended to touch [the corner]."