The First Topic: The Sale of Ribawi Items of the Same Kind on Credit (Deferred Payment)
It is not permissible to sell Ribawi (Usurious ) items of the same kind [96] - The sale of Ribawi items of the same kind is subject to two conditions: First: The exchange must be immediate between both parties. Second: There must be equality according to the prescribed standard, measured by volume and weighed by weight. if one of them is on credit [97] -For example, delaying the exchange in the categories where Ribā usury applies, such as selling gold for gold when one of them is deferred. If the exchange occurs immediately without any increase in one of the two items, then it is permissible. .
The Evidences:
Firstly: From the Sunnah
1. Abu Sa'id Al-Khudri,  رضي الله عنهreported that the Messenger of  Almighty Allah, صلى الله عليه وسلم, said: "Gold for gold, silver for silver, wheat for wheat, barley for barley, dates for dates, and salt for salt, in equal measure, hand to hand. Whoever adds or requests more has engaged in usury (Riba); the receiver and the giver are the same in this matter." [98] - Reported by Muslim(1584).
2. From Ubadah ibn Al-Samit, رضي الله عنه, who reported that the Messenger of Allah, صلى الله عليه وسلم, said: "Gold for gold, silver for silver, wheat for wheat, barley for barley, dates for dates, and salt for salt, in equal measure, equal for equal, hand to hand. If these types differ, sell them as you wish, provided it is hand to hand." [99] -Reported by Muslim(1587).


Secondly: From Consensus
This consensus has been reported by Ibn Al-Mundhir [100] -Ibn al-Mundhir said: "They have unanimously agreed that the six categories of ribā commodities cannot be exchanged in an unequal measure, whether hand-to-hand or deferred; neither of the two is permissible, and it is forbidden." "Al-Ijmāʿ ", p. 97 , Ibn Hazm [101] -Ibn Ḥazm said: "They unanimously agreed that selling gold for gold on a deferred basis is prohibited among Muslims, and that selling silver for silver on a deferred basis is prohibited. They also unanimously agreed that selling wheat for wheat on a deferred basis is prohibited, that selling barley for barley on a deferred basis is prohibited, that selling salt for salt on a deferred basis is prohibited, and that selling dates for dates on a deferred basis is prohibited." "Marātib al-Ijmāʿ", page. 84. , Ibn Abd Al-Barr [102] -Ibn ʿAbd al-Barr said: "It has become settled among the scholars that usury ribā involves increase in gold for gold and in silver for silver, just as it applies in deferred transactions, whether in selling one of them for the other or in selling a part of each one for another. This is a matter of consensus among the scholars, with no disagreement, and it is supported by numerous reports from the Prophet peace and blessings be upon him." "Al-Tamhīd"(6/287). , Ibn Rushd [103] - Ibn Rushd said: "The scholars are in consensus that both disparity tafāḍul and deferment nasāʾ are impermissible in the same category of commodities that were specified in the Hadīth of ʿUbādah ibn al-Ṣāmit." "Bidāyat al-Mujtahid"( 2/129). , Ibn Qudamah [104]-Ibn Qudāmah said: "Any two types that are subject to ribā usury due to the same cause—such as what is measured by volume with what is measured by volume, or what is weighed with what is weighed, or what is foodstuff with what is foodstuff, according to those who attribute this as the cause—then it is prohibited to sell one of them for the other with deferment, without any known disagreement." "Al-Mughnī"(4/9). , and Al-Nawawi [105] -An-Nawawī said: "They have unanimously agreed that it is not permissible to sell ribā commodities of the same type with one of them deferred, and that it is not permissible for there to be disparity when sold of the same kind on the spot, such as gold for gold." Sharh Sahih Muslim, (11/09).         .
The Second Topic: Selling Ribawi Goods of the Same Type with Inequality.
It is not permissible to sell Ribawi usurious goods of the same kind with inequality [106] - For example, if one sells one kilogram of gold for one and a half kilograms of gold, or sells one saa' a specific measure of wheat for one and a half saa's of wheat. .
The Evidences:
Firstly : From the Sunnah:
1. From Abu Sa'id Al-Khudri رضي الله عنه he said: The Messenger of Allah صلى الله عليه وسلم said:  "Gold for gold, silver for silver, wheat for wheat, barley for barley, dates for dates, and salt for salt, like for like, hand to hand. Whoever gives more or asks for more has engaged in Usury (Riba) . The giver and the receiver are equal in this." [107] - Reported by Muslim (1584)   
2. From Ubadah ibn Al-Samit  رضي الله عنه he said: The Messenger of Allah صلى الله عليه وسلم said:  "Gold for gold, silver for silver, wheat for wheat, barley for barley, dates for dates, and salt for salt, like for like, equal for equal, hand to hand. If these types differ, then sell as you wish, provided that it is hand to hand." [108] - Reported by Muslim (1587)
3. From 'Abdur-Rahman ibn Abi Bakrah, who reported that Abu Bakrah رضي الله  عنه said: The Messenger of Allah   صلى الله عليه وسلمsaid:  "Do not sell gold for gold unless it is equal for equal, and do not sell silver for silver unless it is equal for equal. But sell gold for silver and silver for gold as you wish, provided that it is hand to hand." [109] - Narrated by Al-Bukhari (2175) with this wording or text, and by Muslim (1590).
Secondly: From Consensus (Ijma' ) [110] -It was narrated from Ibn Abbas that he held the view of permissibility. However, the scholars have stated that the difference of opinion has ceased and that consensus ijma' has been firmly= =established on the prohibition of Riba al-fadl usurious gain due to inequality in exchange. This has been previously mentioned. See: The Ruling on Riba.
The consensus on this matter has been reported by Ibn Al-Mundhir [111] -Ibn Al-Mundhir said: "They the scholars have unanimously agreed that it is not permissible to deal in the six categories gold, silver, wheat, barley, dates, and salt with inequality, whether hand to hand or on credit; neither of them is allowed, and it is forbidden." "Al-Ijma'", p. 97. ,Al-Kasani [112] -Al-Kasani said: "Selling measured foodstuffs of the same kind with inequality, and selling weighed foodstuffs of the same kind with inequality, like selling one qafiz of rice for two qafizes of rice, or selling one mann of sugar for two manns of sugar, is not permissible by consensus."      "Bada'i' Al-Sana'i'"(5/185). , Ibn Rushd [113] -Ibn Rushd said: "The scholars have unanimously agreed that both inequality and delay in exchange are not permissible in a single type of the categories mentioned in the hadith of Ubadah ibn Al-Samit." " Bidayat Al-Mujtahid"(2/129). , Ibn Qudamah [114] -Ibn Qudamah said: "Riba usury is of two types: Riba al-fadl and riba al-nasi'ah. The scholars have unanimously agreed on the prohibition of both." "Al-Mughni"(4/3). , An-Nawawi [115] - An-Nawawi said: "They the scholars have unanimously agreed that it is not permissible to sell ribawi usurious goods of the same type with one of them deferred, and that inequality is not permissible if it is sold of the same type immediately, like gold for gold." Sharh Sahih Muslim, (11/09). , and Al-Mardawi [116] -Al-Mardawi said: "Ibn Abi Musa mentioned two narrations regarding praying behind someone who drinks nabidh fermented drink believing it to be lawful. He also mentioned that it is not permissible to pray behind someone who says 'water from water,' and it is said: nor behind someone who permits riba al-fadl, such as selling one dirham for two dirhams, because there is now consensus on its prohibition." "Al-Insaf"(2/180). .