Musnad Ahmad 265:6

Ya'qub narrated to us, my father narrated to us, he said: From Ibn Ishaq, he said: Muhammad ibn Ja'far ibn al-Zubayr narrated to me, from the son of Abdullah ibn Unays, from his father, who said: The Messenger of Allah (peace and blessings of Allah be upon him) summoned me and said: "It has reached me that Khalid ibn Sufyan ibn Nubayh al-Hudhali is gathering people against me to fight me, and he is at 'Arana. So go to him and kill him." I said: "O Messenger of Allah, describe him to me so that I may recognize him." He said: "When you see him, you will feel a shudder." He said: So I went out, girded with my sword, until I came upon him while he was at 'Arana with women, looking for a place for them to stay, and it was the time of Asr. When I saw him, I felt the shudder that the Messenger of Allah (peace and blessings of Allah be upon him) had described to me. I approached him, and I feared that there might be a struggle between me and him that would distract me from the prayer, so I prayed while I was walking towards him, gesturing with my head for the bowing and prostration. When I reached him, he said: "Who is the man?" I said: "A man from the Arabs who heard about you and your gathering against this man, so I came to you for that." He said: "Yes, I am in the midst of that." He said: So I walked with him for a while until, when I had the opportunity, I struck him with the sword until I killed him. Then I left, leaving his women leaning over him. When I came to the Messenger of Allah (peace and blessings of Allah be upon him) and he saw me, he said: "The face has succeeded." I said: "I killed him, O Messenger of Allah." He said: "You have spoken the truth." He said: Then the Messenger of Allah (peace and blessings of Allah be upon him) stood up with me and entered his house with me, and he gave me a staff and said: "Keep this with you, O Abdullah ibn Unays." He said: So I went out with it to the people, and they said: "What is this staff?" I said: "The Messenger of Allah (peace and blessings of Allah be upon him) gave it to me and ordered me to keep it." They said: "Will you not return to the Messenger of Allah (peace and blessings of Allah be upon him) and ask him about that?" He said: So I returned to the Messenger of Allah (peace and blessings of Allah be upon him) and said: "O Messenger of Allah, why did you give me this staff?" He said: "It is a sign between me and you on the Day of Resurrection, for the fewest of people on that day will be those who lean on a staff." He said: So Abdullah tied it to his sword, and it remained with him until, when he died, he ordered that it be placed with him in his shroud, and then they were both buried together.