I asked al-Bara' b. Azib about the exchange of (gold for silver or vice versa), whereupon he said: you better ask Zaid b. Arqam for he knows more than I. So I asked Zaid but he said: You better ask al-Bara' for he knows more than I. Then both of them said: Allah's Messenger (ﷺ) forbade the sale of silver for gold when payment is to be made in future.
A necklace having gold and gems in it was brought to Allah's Messenger (ﷺ) in Khaibar and it was one of the spoils of war and was put to sale. Allah's Messenger (ﷺ) said: The gold used in it should be separated, and then Allah's Messenger (ﷺ) further said: (Sell) gold for gold with equal weight.
I bought on the day (of the Victory of Khaibar) a necklace for twelve dinars (gold coins). It was made of gold studded with gems. I separated (gold from gems) in it, and found (gold) of more (worth) than twelve dinars. I made a mention of it to Allah's Apostle (ﷺ), whereupon he said: It should not be sold unless it is separated.
We were in the company of Allah's Messenger ( may peace be upon him) on the day (of the Victory of) Khaibar, and made transaction with the Jews for the 'uqiya of gold for the dinars or three (gold coins), whereupon Allah's Messenger (ﷺ) said: Do not sell gold for gold but for equal weight
We were along with Fadala b. Ubaid (Allah be pleased with him) in an expedition. There fell to my and my friend's lot a necklace made of gold, silver and jewels. I decided to buy that. I asked Fadala b. 'Ubaid, whereupon he said: Separate its gold and place it in one pan (of the balance) and place your gold in the other pan, and do not receive but equal for equal, for I heard Allah's Messenger (ﷺ) as saying: He who believes in Allah and the Hereafter should not take but equal for equal.
Sell it, and then buy with it barley. The slave went away and he got a sa' (of barley) and a part of sa' over and above that. When he came to Ma'mar he informed him about that, whereupon Ma'mar said to him: Why did you do that? Go back and return that, and do not accept but weight, for weight, for I used to hear from Allah's Apostle (ﷺ) as saying: Wheat for wheat and like for like. He (one of the narrators) said: Our food in those days consisted of barley. It was said to him (Ma'mar) that (wheat) is not like that (barley). He replied: I am afraid these may not be similar
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ بْنِ قَعْنَبٍ، حَدَّثَنَا سُلَيْمَانُ، - يَعْنِي ابْنَ بِلاَلٍ - عَنْ عَبْدِ الْمَجِيدِ بْنِ سُهَيْلِ بْنِ عَبْدِ الرَّحْمَنِ، أَنَّهُ سَمِعَ سَعِيدَ بْنَ الْمُسَيَّبِ، يُحَدِّثُ أَنَّ أَبَا هُرَيْرَةَ، وَأَبَا سَعِيدٍ حَدَّثَاهُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم بَعَثَ أَخَا بَنِي عَدِيٍّ الأَنْصَارِيَّ فَاسْتَعْمَلَهُ عَلَى خَيْبَرَ فَقَدِمَ بِتَمْرٍ جَنِيبٍ فَقَالَ لَهُ رَسُولُ اللَّهِ صلى الله عليه وسلم " أَكُلُّ تَمْرِ خَيْبَرَ هَكَذَا " . قَالَ لاَ وَاللَّهِ يَا رَسُولَ اللَّهِ إِنَّا لَنَشْتَرِي الصَّاعَ بِالصَّاعَيْنِ مِنَ الْجَمْعِ . فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لاَ تَفْعَلُوا وَلَكِنْ مِثْلاً بِمِثْلٍ أَوْ بِيعُوا هَذَا وَاشْتَرُوا بِثَمَنِهِ مِنْ هَذَا وَكَذَلِكَ الْمِيزَانُ " .
Are all the dates of Khaibar like this? He said: Allah's Messenger, it is not so. We buy one sa' of (fine quality of dates) for two sa's out of total output (including even the inferior quality of dates), whereupon Allah's Messenger (ﷺ) said: Don't do that, but like for like, or sell this (the inferior quality and receive the price) and then buy with the price of that, and that would make up the measure.