Abu Ayash Zaid reports: He asked Sayyiduna Sa’d bin Abi Waqqas (may Allah be pleased with him) about exchanging one type of barley for another type. He asked which of the two is superior. He replied: The white one. Then Sayyiduna Sa’d bin Abi Waqqas (may Allah be pleased with him) forbade him from this and explained that he had heard the Noble Prophet (peace and blessings be upon him). He was asked about selling fresh dates in exchange for dry dates. The Noble Prophet (peace and blessings be upon him) asked: Do fresh dates decrease in quantity when they dry? The questioner replied: Yes. So the Noble Prophet (peace and blessings be upon him) forbade him from this.

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates from Sayyiduna Zaid bin Thabit (may Allah be pleased with him): The Prophet Muhammad (peace and blessings be upon him) permitted the sale of ‘Ariya (fresh dates on the tree in exchange for dry dates) based on estimation.

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates from Sayyiduna Zaid bin Thabit (may Allah be pleased with him) regarding the Prophet Muhammad (peace and blessings be upon him): He permitted the sale of ‘Araya based on estimation.

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates: The Prophet (peace and blessings of Allah be upon him) permitted the sale of ‘Araya when it is less than five wasq (the narrator is in doubt, or perhaps these are the words:) when it is five wasq.

(Imam Ibn Hibban, may Allah have mercy on him, says:) The doubt regarding either of these two numbers is from the narrator named Dawud bin Husayn.

Sayyiduna Abu Huraira (may Allah be pleased with him) narrates: The Prophet (peace and blessings of Allah be upon him) permitted the sale of ‘Araya, when it is less than five wasqs (the narrator is in doubt, or perhaps the words are:) five wasqs.

Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) narrates: I heard the Prophet Muhammad (peace be upon him). When he permitted the sale of ‘Araya based on estimation. The Prophet Muhammad (peace be upon him) said: (It can be sold) when it is one wasq or two wasqs, or three or four.

Sayyiduna Zaid bin Thabit (may Allah be pleased with him) narrates: The Prophet Muhammad (peace and blessings be upon him) permitted the sale of ‘Ariya (fresh dates on the tree exchanged for dried dates) based on estimation. He did not permit anything besides this.

Sayyiduna Khabbab (may Allah be pleased with him) narrates: I was a blacksmith in Makkah. I made a sword for ‘As bin Wa’il. I went to him to demand (the price for it), so he said: I will not pay you until you disbelieve in Muhammad (peace be upon him). I said: I will not disbelieve in Muhammad (peace be upon him) until Allah gives you life again. He said: When Allah gives me death and then brings me back to life, at that time I will have wealth and children, so I will pay you. (Sayyiduna Khabbab, may Allah be pleased with him, narrates) I mentioned this to the Prophet (peace be upon him), so Allah revealed this verse:“Have you seen the one who disbelieves in Our verses and says: I will surely be given wealth and children?”

(Imam Ibn Hibban, may Allah have mercy on him, says:) If the hearts of those who hear these words are inclined towards this—meaning these words that I made a sword for ‘As bin Wa’il and then I went to him to demand (its price)—(so the listener thinks) that trading in Dar al-Harb is permissible and that it is permissible for a Muslim to buy and sell with a Harbi, as long as he benefits the Muslims with its price, then it should be known that this is a weak deduction and a harmful argument. The reason is that when Sayyiduna Khabbab (may Allah be pleased with him) made this sword for ‘As bin Wa’il, at that time Allah had not revealed the verse regarding the command of fighting, nor had jihad been made obligatory. The reason is that the obligation of jihad and the command to fight the polytheists was revealed after the Prophet (peace be upon him) left Makkah, as we have mentioned earlier, and this incident of Sayyiduna Khabbab (may Allah be pleased with him) is from Makkah, which is before Allah made jihad obligatory upon the people.

Sayyiduna Mu’ammar bin Abdullah (may Allah be pleased with him) narrates: He sent his slave with one sa’ of barley and said: Go and sell it, and whatever barley you get in exchange, bring it back. The boy went and obtained one sa’ and a little more barley. When he came to Mu’ammar and informed him about it, Mu’ammar said to him: Why did you do this? Go and return it, and only take an equal amount, because I heard the Prophet (peace and blessings of Allah be upon him) say:“When exchanging grain for grain, it must be equal.”And in those days, our grain was barley.

Sayyiduna Abu Hurairah, may Allah be pleased with him, narrates this statement of the Prophet Muhammad, peace and blessings be upon him: "There will be no extra payment when exchanging dinar for dinar, or dirham for dirham."