Musnad Ahmad 22:43

Waki’ narrated to us, Abu Isra’il al-‘Absi narrated to us, from Fudayl ibn ‘Amr, from Sa’id ibn Jubayr, from Ibn ‘Abbas, from al-Fadl, or one of them from the other, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever intends the Hajj, let him hasten, for the sick person may become ill, the stray animal may be lost, and a need may arise."