Zayd Abu 'Ayyash asked Sa'd ibn Abi Waqqas about the sale of the soft and white kind of wheat for barley. Sa'd said:

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.

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ، عَنْ مَالِكٍ، عَنْ عَبْدِ اللَّهِ بْنِ يَزِيدَ، أَنَّ زَيْدًا أَبَا عَيَّاشٍ، أَخْبَرَهُ أَنَّهُ، سَأَلَ سَعْدَ بْنَ أَبِي وَقَّاصٍ عَنِ الْبَيْضَاءِ، بِالسُّلْتِ فَقَالَ لَهُ سَعْدٌ أَيُّهُمَا أَفْضَلُ قَالَ الْبَيْضَاءُ . فَنَهَاهُ عَنْ ذَلِكَ 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 . قَالَ أَبُو دَاوُدَ رَوَاهُ إِسْمَاعِيلُ بْنُ أُمَيَّةَ نَحْوَ مَالِكٍ .