Hadith 648:4
Yahya ibn Abd al-Malik ibn Abi Ghaniyah narrated to us, he said: Uqbah ibn al-Mughirah narrated to us, from the grandfather of his father, al-Mukhariq, who said: I met Ammar on the day of the Camel while he was urinating into a horn. I said, "Shall I fight with you and be with you?" He said, "Fight under the banner of your people, for the Messenger of Allah, peace and blessings of Allah be upon him, used to like for a man to fight under the banner of his people."
حدثنا يحيى بن عبد الملك بن أبي غنية، قال: حدثنا عقبة بن المغيرة، عن جد أبيه المخارق، قال: لقيت عمارا يوم الجمل وهو يبول في قرن، فقلت: أقاتل معك فأكون معك؟ قال: " قاتل تحت راية قومك، فإن رسول الله صلى الله عليه وسلم كان يستحب للرجل أن يقاتل تحت راية قومه "