Musnad Ahmad 27:680

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, I heard Abu Ishaq, I heard a man from the people of Najran who said: I asked Ibn 'Umar, I said: "I am only asking you about two things: about the *salam* (forward sale) in date palms, and about raisins and dates." He said: A man who was intoxicated, having drunk [a mixture of] raisins and dates, was brought to the Messenger of Allah (ﷺ). He said: So he flogged him the prescribed punishment, and he forbade that they be mixed. He said: A man made a *salam* contract for the date palms of a man, but his date palms did not bear fruit. He said: So he came to him demanding it. He said: He refused to give it to him. He said: So they both came to the Prophet (ﷺ), and he said: "Did your date palms bear fruit?" He said: "No." He said: "Then by what [right] do you consume his wealth?" He said: So he commanded him, and he returned it to him, and he forbade the *salam* in date palms until their ripeness becomes apparent.