Which of them is better? He replied: Soft and white kind of wheat. So he forbade him from it and said: I heard the Messenger of Allah (sawa) say, when he was asked about buying dry dates for fresh. The Messenger of Allah (sawa) said: Are fresh dates diminished when they become dry? The (the people) replied: Yes. So the Messenger of Allah ﷺ forbade that. Abu Dawud said: A similar tradition has also been transmitted by Isma'il b. Umayyah.  

وَقَالَ سَمِعْتُ رَسُولَ اللَّهِ ﷺ يُسْأَلُ عَنْ شِرَاءِ التَّمْرِ بِالرُّطَبِ فَقَالَ رَسُولُ اللَّهِ ﷺ أَيَنْقُصُ الرُّطَبُ إِذَا يَبِسَ قَالُوا نَعَمْ فَنَهَاهُ رَسُولُ اللَّهِ ﷺ عَنْ ذَلِكَ  

The Messenger of Allah ﷺ forbade to sell fresh dates for dry dates when payment is made at a later date. Abu Dawud said: The tradition mentioned above has also been transmitted by Sa'd (b. Abi Waqqas) from the Prophet ﷺ through a different chain of narrators in a similar way.  

أَخْبَرَهُ أَنَّهُ سَمِعَ سَعْدَ بْنَ أَبِي وَقَّاصٍ يَقُولُ نَهَى رَسُولُ اللَّهِ ﷺ عَنْ بَيْعِ الرُّطَبِ بِالتَّمْرِ نَسِيئَةً