Musannaf Ibn Abi Shayba 8:3007

Abu Bakr narrated to us, he said: Ibn Fudayl narrated to us, from ‘Umar ibn Dharr, from ‘Abd al-Malik ibn al-Harith, from ‘Uqbah, the freed slave of Adhlam ibn Na‘amah al-Hadrami, that he departed with al-Husayn ibn ‘Ali from Jam‘ (Muzdalifah), and he did not increase his pace. When he reached Wadi Muhassir, he said: "Raise your voice, urge your mount with your leg, and strike with your whip." He then urged his mount through the valley until the ground became level for him, and he exited the valley.