Sunan an-Nasa'i 4571
سنن النسائي#4571SahihIt was narrated that Abu Saeed Al-Khudri said:"My eyes saw and my ears heard the Messenger of Allah. And he mentioned the prohibition of (selling) gold for gold and silver for silver, unless it is equal amounts, like for like. And do not sell it in return for something to be paid later, and do not differentiate
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiHasan
In-book reference: 44:123