Concerning currency exchange, he said, Abu Saeed arrived and stayed at this house, so Ibn Umar took me by the hand along with the other man until we came to Abu Saeed. He stood before him and asked, "What is this man reporting to me from you?"Abu Saeed replied, "Yes, with my own eyes I saw and with my own ears I heard," pointing with his finger to his eyes and ears. I have never forgotten his gesture with his two fingers, from the Messenger of Allah ﷺ, that he forbade exchanging gold for gold or silver for silver except equally, like for like. Do not sell what is not present for what is present, and do not give one of them an advantage over the other.
حدثنا يزيد بن هارون أخبرنا ابن عون عن نافع قال كان رجل يحدث ابن عمر بحديث
في الصرف قال فقدم أبو سعيد فنزل هذه الدار فأخذ ابن عمر بيدي ويد الرجل حتى أتينا أبا سعيد فقام عليه فقال ما يحدثني هذا عنك فقال أبو سعيد نعم بصر عيني وسمع أذني وأشار بإصبعه إلى عينيه وأذنيه فما نسيت قوله بإصبعيه من رسول الله ﷺ أنه نهى عن الذهب بالذهب والورق بالورق إلا سواء بسواء مثلا بمثل ألا لا تبيعوا غائبا بناجز ولا تشفوا أحدهما على الآخر
Its chain of transmission is sahih. Ibn Umar here is Abdullah bin Umar bin Hafs bin Asim al-Umari, who narrates from Nafi and al-Maqburi. He is truthful and there is no harm in him. The hadith has already appeared at 10948.