Sahih Muslim 1593
Sahih Muslim · Book 22: The Book of Musaqah · Selling Food Like for Like
Abu Huraira (Allah be pleased with him) reported that Allah's Messenger (ﷺ) deputed a person to collect revenue from Khaibar. He brought fine quality of dates, whereupon Allah's Messenger (ﷺ) said:
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى ، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ عَبْدِ الْمَجِيدِ بْنِ سُهَيْلِ بْنِ عَبْدِ، الرَّحْمَنِ بْنِ عَوْفٍ عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ ، وَعَنْ أَبِي هُرَيْرَةَ ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم اسْتَعْمَلَ رَجُلاً عَلَى خَيْبَرَ فَجَاءَهُ بِتَمْرٍ جَنِيبٍ فَقَالَ لَهُ رَسُولُ اللَّهِ صلى الله عليه وسلم " أَكُلُّ تَمْرِ خَيْبَرَ هَكَذَا " . فَقَالَ لاَ وَاللَّهِ يَا رَسُولَ اللَّهِ إِنَّا لَنَأْخُذُ الصَّاعَ مِنْ هَذَا بِالصَّاعَيْنِ وَالصَّاعَيْنِ بِالثَّلاَثَةِ . فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " فَلاَ تَفْعَلْ بِعِ الْجَمْعَ بِالدَّرَاهِمِ ثُمَّ ابْتَعْ بِالدَّرَاهِمِ جَنِيبًا " .
Are all the dates of Khaibar like this)? He said: No. We got one sa' (of fine dates) for two sa's (of inferior dates), and (similarly) two sa's for three sa's. Thereupon Allah's Messenger (ﷺ) said: Don't do that rather sell the inferior quality of dates for dirhams (money), and then buy the superior quality with the help of dirhams.