Musnad Ahmad 27:1287

'Ali ibn Bahr narrated to us, 'Isa ibn Yunus narrated to us, from 'Ubayd Allah, from Nafi', from Ibn 'Umar, who said: "When the Messenger of Allah (peace and blessings of Allah be upon him) performed the first circumambulation (Tawaf), he would jog for three (laps) and walk for four. And he would trot in the bottom of the valley (Masīl) when he performed the Sa'i between Safa and Marwa."