Grading: Its chain is hasan
Note / Clarification: Ayyub is Ayyub bin Abi Tamimah al-Sakhtiyani.

Reference / Source: Imam al-Nasa'i narrated it at (6160) through Amr bin Ali al-Fallas and Humayd bin Mas'adah, from Yazid bin Zuray', with this same chain; except for the words: "wa la ribhu ma lam yudman" (nor profit on that for which liability/risk has not been taken on).

Reference / Source: Ibn Majah narrated it at (2188) through Azhar bin Marwan, from Hammad bin Zayd, with this same chain; but it does not mention credit and sale (salaf and bay') or two conditions in one sale.

Reference / Source: Imam Ahmad (11/ 6671), Abu Dawud (3504), Ibn Majah (2188), al-Tirmidhi (1234) and al-Nasa'i (6181) narrated it through the route of Isma'il Ibn Ulayyah, from Ayyub al-Sakhtiyani, with this same chain
Grading: Imam al-Tirmidhi called it "hasan sahih".

Guidance: Also see the narration that comes after it.

General principle: His (peace and blessings be upon him) saying "la yahillu salafun wa bay'" (credit and sale are not lawful) falls under the chapter of the prohibition of two sales in one sale, for example someone says: I sell you this slave for fifty dinars on condition that you advance me a thousand dirhams for goods that I will sell you for a set term, or that you lend me a thousand dirhams; here salaf means "loan"
Important point: This deal is invalid (fasid) because he is lending to him on condition that he gives him a concession in the price, so the price enters the bounds of uncertainty (jahalah); also because every loan that draws a benefit is "riba" (usury); and also because the contract (agreement) contains a condition that does not allow it to remain valid.

General principle: His (peace and blessings be upon him) saying "wa la shartani fi bay'" (nor two conditions in one sale) is also of the same standing as two sales in one sale, for example he says: I have sold you this cloth for one dinar in cash and for two dinars on credit; so this is a sale containing two conditions whose purpose changes with the difference in prices, which brings "gharar" (deceptive uncertainty) and uncertainty into it
Note / Clarification: According to most scholars there is no difference in this matter between one condition, two or more, because the cause ('illah) is one; however, Imam Ahmad distinguished between one and two conditions, acting on the apparent wording of the hadith.

General principle: What is meant by these conditions is those which contradict the requirements of the sale and invalidate it, such as conditions that take the price into the bounds of uncertainty, or that create deceptive uncertainty (gharar) in the contract or in the handover, or that prevent the buyer from the right of ownership
Note / Clarification: Conditions that serve the interest of the contract or accord with its requirements do not fall under this prohibition, so they are permissible.

General principle: His (peace and blessings be upon him) saying "wa la ribhu ma lam yudman" (nor profit on that for which liability/daman has not been taken on) means that a person sells something he has bought but has not yet taken possession of, so it is still under the liability (daman) of the first seller and has not come under his own liability; therefore selling such a thing before taking possession is not permissible, until it comes under his liability.

General principle: His (peace and blessings be upon him) saying "wa la bay'u ma laysa 'indak" (do not sell what is not with you) refers to the sale of a specific item ('ayn), not a sale on the basis of description (bay' al-sifah); that is, selling something that is not present with the seller at the time. Included in this is everything that the seller is not responsible for procuring, such as selling another person's property contingent on the owner's permission
Technical note / Defect ('illah): The reason for all these prohibitions is deceptive uncertainty (gharar) and the possibility of existence or non-existence
Reference / Source: All these points were set out by Imam al-Khattabi in "Ma'alim al-Sunan" (3/ 140-143) and by Ibn al-Athir in "al-Nihayah" under the entries (salaf, shart and daman).