Mu'awiyah went on Hajj and he called a group of Ansar to the Ka'bah. He said: 'I adjure you by Allah, did you hear the Messenger of Allah [SAW] forbid gold?' They said: 'Yes.' He said: 'And I bear witness to that.'" (Using translation from Nasāʾī 5156)
«أَنْشُدُكُمْ بِاللهِ أَلَمْ تَسْمَعُوا رَسُولَ اللهِ ﷺ يَنْهَى عَنِ الذَّهَبِ؟» قَالُوا اللهُمَّ نَعَمْ قَالَ «وَأَنَا أَشْهَدُ»