"Ubadah bin Samit and Mu'awiyah happened to meet, either in a church or in a synagogue. 'Ubadah bin Samit narrated to them and said: 'The Messenger of Allah (ﷺ) forbade us from selling silver for silver, gold for gold, wheat for wheat, barley for barley, and dates for dates.'I one of them said: "And salt for salt," but the other did not say it. "And he commanded us to sell wheat for barley, or barley for wheat, hand-to-hand, however we wished."
Sunan Ibn Majah Book 12, Hadith 118
O, son of Adam, did you find any comfort, did you happen to get any material blessing? He would say: By Allah, no, my Lord. And then that person from amongst the persons of the world be brought who had led the most miserable life (in the world) from amongst the inmates of Paradise. and he would be made to dip once in Paradise and it would be said to him. 0, son of Adam, did you face, any hardship? Or had any distress fallen to your lot? And he would say: By Allah, no,0 my Lord, never did I face any hardship or experience any distress.
Sahih Muslim Book 52, Hadith 42