Sayyiduna Jabir (may Allah be pleased with him), speaking about the Hajj of the Prophet (peace and blessings be upon him), said: Then he (peace and blessings be upon him) remained standing there until the sun set and some of the yellowness had also gone. Then he (peace and blessings be upon him) seated Sayyiduna Usamah bin Zayd (may Allah be pleased with him) behind him and set off from there, pulling in the rein of al-Qaswa' until her head was touching the corner of the saddle, and he (peace and blessings be upon him) was saying with his right hand: "Calmly, calmly." Whenever he came to a hill, he would loosen (the rein) a little until she had climbed it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9482