From Sahih Muslim (Hadith 3849):
Abu Huraira (Allah be please with him) is reported to have said to Marwan:Have you made lawful the transactions involving interest? Thereupon Marwan said: I have not done that. Thereupon Abu Huraira (ﷺ) said: You have made lawful the transactions with the help of documents only, whereas Allah's Messenger (ﷺ) forbade the transaction of foodgrains until full possession is taken of them. Marwan then addressed the people and forbade them to enter into such transactions (as are done with the help of documents). Sulaiman said: I saw the sentinels snatching (these documents) from the people
Reference: Muslim 3849