Abdullah bin 'Awn bin Artaban عبد الله بن عون بن أرطبان الخزار · The Chapters on Business Transactions

"The two parties to a transaction have the choice (of annulling it) so long as they have not yet parted. "

"The Messenger of Allah (ﷺ) said: 'Whoever buys food, let him not sell it until he has taken full possession of it.'" (Sahih) In his narration, (one of the narrators) Abu 'Awanah said: "Ibn 'Abbas said: 'I think everything is like food."'

"The last thing to be revealed was the Verse on usury but the Messenger of Allah (ﷺ) died before he had explained it to us. So give up usury (interest) and doubtful things."