Messenger of Allah ﷺ appointed a man as the ruler of Khaibar who later brought some Janib (i.e. dates of good quality) to the Prophet. On that, Messenger of Allah ﷺ said (to him). "Are all the dates of Khaibar like this?" He said, "No, by Allah, O Messenger of Allah ﷺ! But we take one Sa of these (dates of good quality) for two or three Sa's of other dates (of inferior quality)." On that, Messenger of Allah ﷺ said, "Do not do so, but first sell the inferior quality dates for money and then with that money, buy Janib."
عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ وَأَبِي هُرَيْرَةَ ؓ أَنَّ رَسُولَ اللَّهِ ﷺ اسْتَعْمَلَ رَجُلاً عَلَى خَيْبَرَ فَجَاءَهُ بِتَمْرٍ جَنِيبٍ فَقَالَ رَسُولُ اللَّهِ ﷺ كُلُّ تَمْرِ خَيْبَرَ هَكَذَا فَقَالَ لاَ وَاللَّهِ يَا رَسُولَ اللَّهِ إِنَّا لَنَأْخُذُ الصَّاعَ مِنْ هَذَا بِالصَّاعَيْنِ {وَالصَّاعَيْنِ} بِالثَّلاَثَةِ فَقَالَ لاَ تَفْعَلْ بِعِ الْجَمْعَ بِالدَّرَاهِمِ ثُمَّ ابْتَعْ بِالدَّرَاهِمِ جَنِيبًا