Sunan an-Nasa'i, Book 44, Hadith 120 (In-Book) ⓘ
It was narrated that Mujahid said: "Umar said: Dinar for Dinar, Dirham for Dirham, no difference between them, this is the obligation that our Prophet enjoined upon us."
أَخْبَرَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، عَنْ مَالِكٍ، عَنْ حُمَيْدِ بْنِ قَيْسٍ الْمَكِّيِّ، عَنْ مُجَاهِدٍ، قَالَ قَالَ ابْنُ عُمَرَ الدِّينَارُ بِالدِّينَارِ وَالدِّرْهَمُ بِالدِّرْهَمِ لاَ فَضْلَ بَيْنَهُمَا هَذَا عَهْدُ نَبِيِّنَا صلى الله عليه وسلم إِلَيْنَا .
also referenced under: Hadith 4568 (Reference) & Volume 5, Book 44, Hadith 4572 (DarusSalam)