Musnad Ahmad 25:827

Yunus narrated to us, Hammad—meaning Ibn Zayd—narrated to us, Ayyub narrated to us, from Sa’id ibn Jubayr, from Ibn Abbas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) and his companions arrived in Makkah, and the fever of Yathrib had weakened them. The polytheists said: "A people have come to you whom the fever of Yathrib has weakened, and they have suffered evil from it." The polytheists sat on the side that adjoins the Hijr. Allah informed His Prophet of what they had said. The Messenger of Allah (peace and blessings of Allah be upon him) commanded them to perform *ramal* (brisk walking) during the three circuits, so that the polytheists might see their strength. He said: So they performed *ramal* for three circuits. He commanded them to walk between the two corners where the polytheists could not see them. Ibn Abbas said: The Prophet (peace and blessings of Allah be upon him) was not prevented from commanding them to perform *ramal* during all the circuits except out of compassion for them. The polytheists said: "Are these the ones you claimed the fever had weakened? These are stronger than such and such."