He was a freed slave of Persian origin. He said, "I was present with the Messenger of Allah ﷺ at Uhud, and I struck one of the polytheists, saying, 'Take this from me, for I am the Persian lad!' The Messenger of Allah ﷺ turned to me and said, 'Why did you not say, Take this from me, for I am the Ansari lad?'"
حدثنا محمد بن عبد الرحيم حدثنا الحسين بن محمد حدثنا جرير بن حازم عن محمد بن إسحق عن داود بن حصين عن عبد الرحمن بن أبي عقبة
وكان مولى من أهل فارس قال شهدت مع رسول الله ﷺ أحدا فضربت رجلا من المشركين فقلت خذها مني وأنا الغلام الفارسي فالتفت إلي رسول الله ﷺ فقال فهلا قلت خذها مني وأنا الغلام الأنصاري
[Its chain is daif] Ibn Majah narrated it in jihad, chapter on intention in fighting, no. 2784, from the hadith of Husayn bin Muhammad, through this same chain. Ibn Ishaq narrated with "an" without specifying direct hearing, and Abdul-Rahman bin Abu Uqbah is obscure, with no one confirming his reliability except Ibn Hibban.