Musnad Ahmad 30:2074

Ishaq ibn Ibrahim al-Razi, the son-in-law of Salamah al-Abrash, narrated to us, saying: Salamah ibn al-Fadl narrated to us, saying: Muhammad ibn Ishaq narrated to me, from his paternal uncle Musa ibn Yasar, from Abu Hurayrah, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "Do not wish to meet the enemy, for you do not know what will happen in that."