Nasai

Urdu marginal note:
Remember, this applies when the two sides are of different kinds, for example: gold in exchange for silver or silver in exchange for gold. Otherwise, if the kind is the same on both sides, then any excess or deficiency is also usury (riba), as is explicitly established in the narrations.

Hadith Commentary:
The school of thought of Abdullah ibn Abbas radi Allahu anhu is that usury (riba) occurs when there is a delay (i.e., one side is deferred). If cash is exchanged—one dirham for two dirhams—this is permissible. The evidence of Ibn Abbas radi Allahu anhu is this hadith:
“There is no riba except in deferment (nasi’ah).”
When objections were raised to this fatwa of Abdullah ibn Abbas radi Allahu anhu, he said: “I do not claim that I found this ruling in the Book of Allah, nor do I claim that I heard it from the Messenger of Allah sallallahu alayhi wa sallam, because at that time I was a child and you were young men. You used to spend day and night in the blessed company of the Prophet sallallahu alayhi wa sallam.”
Qastallani rahimahullah said that now there is consensus (ijma’) against the fatwa of Abdullah ibn Abbas radi Allahu anhu.
Some have said that this is to be understood in the case when the types (of commodities) are different, such as when on one side there is silver and on the other side gold, or on one side wheat and on the other barley; in such a situation, disparity is permissible.
Some have said that the hadith “There is no riba except in deferment (nasi’ah)” is abrogated (mansukh), but abrogation cannot be established merely on the basis of possibility.
In Sahih Muslim, it is narrated from Ibn Abbas radi Allahu anhu that there is no riba in a sale that is hand to hand (immediate exchange).
Some have also said that Abdullah ibn Abbas radi Allahu anhu retracted this statement.
Imam Shawkani says:
“And Hazimi has narrated the retraction (ruju’) of Ibn Abbas and his seeking forgiveness when he heard Umar ibn al-Khattab radi Allahu anhu and his son Abdullah narrating from the Messenger of Allah sallallahu alayhi wa sallam what indicates the prohibition of riba al-fadl (usury of excess). He said regretfully: ‘You have preserved from the Messenger of Allah sallallahu alayhi wa sallam what I did not preserve.’ And Hazimi also narrated from him that he said: ‘That was my opinion, and here is Abu Sa’id al-Khudri radi Allahu anhu narrating to me from the Messenger of Allah sallallahu alayhi wa sallam, so I abandoned my opinion for the hadith of the Messenger of Allah sallallahu alayhi wa sallam,’ etc.”
That is, Hazimi has transmitted the retraction and seeking forgiveness of Ibn Abbas radi Allahu anhu when he heard the statement of the Messenger of Allah sallallahu alayhi wa sallam regarding the prohibition of this sale from Umar ibn al-Khattab radi Allahu anhu and his son. He regretfully said: “You people preserved the statement of the Messenger, but alas, I could not preserve it.”
And according to the narration of Hazimi, he also said: “What I said was only my opinion, and after hearing the hadith of the Prophet from Abu Sa’id al-Khudri radi Allahu anhu, I abandoned my opinion.”
Integrity demands that when the clear texts of the Qur’an and hadith are presented, no opinion or analogy should be considered as proof, and the Book and Sunnah should be given precedence—even if the opinions of the great Imams of the religion appear contrary to the clear texts, then with utmost respect and reverence, the Book and Sunnah should be given precedence over opinions.
The Imams of Islam—Imam Abu Hanifah, Imam Shafi’i, Imam Malik, and Imam Ahmad ibn Hanbal rahimahumullah—all have said: “Present our fatwas before the Book and Sunnah; if they are in agreement, accept them. If they appear contrary, then give precedence to the Book and Sunnah.”
Imam al-Hind Shah Waliullah Muhaddith Dehlawi rahimahullah, in his esteemed book Hujjatullah al-Balighah, has quoted such statements of the Imams in several places. But, alas, a large segment of the Ummah is such that it is severely afflicted with rigidity within its own circle of allegiance, and is not prepared to accept any verse of the Noble Qur’an or any clear, explicit hadith of the Prophet that goes against its supposed school of thought.
Hali marhoom has said regarding such people:
Forever there is resentment in the hearts of the people of research,
They think following hadiths causes harm to the religion,
Their entire practice is based solely on fatwas,
Every opinion is considered a substitute for the Qur’an,
Neither faith remains, nor Islam remains,
Only the name of Islam remains.

Hadith Commentary:
When there is an exchange between items of the same kind, it must be equal for equal and hand to hand. However, the position of Abdullah ibn Abbas (radi Allahu anhu) was that in a hand-to-hand transaction, it is permissible to sell one dinar for two dinars. According to him, usury (riba) only existed when there was delay from one side.

When Abu Sa'id al-Khudri (radi Allahu anhu) met him, he said:
Ibn Abbas! You should fear Allah. How long will you continue to make people consume usury? Then he narrated this hadith: The Messenger of Allah (sallallahu alayhi wa sallam) said: "It is permissible to sell dates for dates, wheat for wheat, barley for barley, gold for gold, and silver for silver, provided it is equal for equal and hand to hand. Whoever takes more has engaged in usury." Upon hearing this Prophetic hadith, Ibn Abbas (radi Allahu anhu) said: Abu Sa'id! May Allah grant you Paradise! You have reminded me of something I had forgotten. I seek forgiveness from Allah and turn to Him in repentance.

After this, Ibn Abbas (radi Allahu anhu) forbade it very strictly.
(al-Mustadrak lil-Hakim: 2/43)

Since the position of Ibn Abbas (radi Allahu anhu) was contrary to other authentic ahadith, he retracted his view. However, the hadith narrated from Ibn Abbas (radi Allahu anhu) is also authentic. The following interpretations have been made of it:
➊ There is no usury more severe than that which is in deferred payment.
➋ What is meant is the exchange of different kinds of commodities, where usury only occurs in deferred transactions, and disparity in quantity is permissible.

And Allah knows best.

Hadith Commentary: Benefits and Issues: The meaning of this hadith could also be that the riba (usury/interest) which is strictly prohibited in the Qur'an with severe warnings is related only to riba al-nasi’ah (usury of delay), not to riba al-fadl (usury of excess). Or, according to the position of the Zahiri school, riba al-fadl pertains only to the six items mentioned in the hadith, and in other items, increase or decrease is permissible, only deferred payment is impermissible. However, Ibn Abbas (radi Allahu anhuma) considered this to be general, and thus declared excess to be permissible even in the case of the same kind.

(1) Silver can be bought and sold in exchange for gold, or gold in exchange for silver, on the condition that payment is made on the spot by both parties.

(2) From this blessed hadith, it is also understood that a religious scholar, when discussing a religious issue with another scholar, should do so with evidence, and every person has the right to ask a scholar whether the issue he has stated is found in the Noble Qur’an or established from the hadith of the Messenger (sallallahu alayhi wa sallam), because the original sources of the rulings of the Shari‘ah are the Qur’an and Sunnah. Furthermore, the one being questioned (the person from whom such a question is asked) should not consider this type of question—i.e., being asked for evidence—as “disrespect to his status,” but rather should answer without delay, just as when Abu Sa‘id al-Khudri (radi Allahu anhu) asked, our master Abdullah ibn Abbas (radi Allahu anhu) immediately replied that Usamah ibn Zayd (radi Allahu anhu) had informed him of this.

(3) This blessed hadith guides us that it is the duty of the religious scholar to bring back to the community any person who has separated from it, and this duty should be fulfilled through the evidences of the Book and the Sunnah.

(4) “What you are saying”—in reality, Abdullah ibn Abbas (radi Allahu anhu) misunderstood from the narration of Usamah ibn Zayd (radi Allahu anhu) that gold could be bought and sold for gold, and silver for silver, even with an increase or decrease, as long as it was not on credit. However, this hadith is about a specific situation, i.e., when the two parties’ commodities are different, for example: silver in exchange for gold, as has been indicated in the above hadith (4584). Such meanings cannot be derived from a single narration that contradict clear, detailed, and numerous other narrations. Some ahadith are concise; to understand their meanings, one must refer to other detailed narrations.