It was narrated that Ibn ‘Umar said: “I used to sell gold for silver, or silver for gold. I came to the Messenger of Allah صلی اللہ علیہ وآلہ وسلم and told him about that, and he said: ‘If you make a deal with your Companion, do not leave him when there is still any ambiguity (in the deal) between you.” (Hasan)