Musnad Ahmad 27:1918

Abu al-Yaman narrated to us, Shu'ayb informed us, he said: I asked al-Zuhri? He said: Salim informed me that Abdullah ibn Umar said: I went on a military expedition with the Messenger of Allah, may Allah bless him and grant him peace, an expedition towards Najd. We drew parallel to the enemy and we lined up against them. Then he mentioned the rest of the hadith.